ded
/
cpp-httplib
同期ミラー https://github.com/yhirose/cpp-httplib.git


			
				
					
						
						
							123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529
							<!DOCTYPE html>
<html lang="ja" data-base-path="&#x2F;cpp-httplib">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Basic Client - cpp-httplib</title>
  <link rel="icon" type="image/svg+xml" href="&#x2F;cpp-httplib/favicon.svg">
  <link rel="stylesheet" href="&#x2F;cpp-httplib/css/main.css">
  <script>
    (function() {
      var t = localStorage.getItem('preferred-theme');
      if (!t) t = window.matchMedia('(prefers-color-scheme: light)').matches ? 'light' : 'dark';
      if (t === 'light') document.documentElement.setAttribute('data-theme', 'light');
    })();
  </script>
</head>
<body>
  <header class="header">
    <div class="header-inner">
      <a href="&#x2F;cpp-httplib&#x2F;ja/" class="header-title">cpp-httplib <span style="font-size:0.75em;font-weight:normal;margin-left:4px">v0.36.0</span></a>
      <div class="header-spacer"></div>
      <nav class="header-nav">
        <a href="&#x2F;cpp-httplib&#x2F;ja/">
          <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M3 9l9-7 9 7v11a2 2 0 0 1-2 2H5a2 2 0 0 1-2-2z"/><polyline points="9 22 9 12 15 12 15 22"/></svg>
          Home
        </a>
        
        
        <a href="&#x2F;cpp-httplib&#x2F;ja/tour&#x2F;">
          <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="10"/><polygon points="16.24 7.76 14.12 14.12 7.76 16.24 9.88 9.88 16.24 7.76"/></svg>
          Tour
        </a>
        
        
        
        <a href="https:&#x2F;&#x2F;github.com&#x2F;yhirose&#x2F;cpp-httplib" aria-label="GitHub">
          <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><path d="M9 19c-5 1.5-5-2.5-7-3m14 6v-3.87a3.37 3.37 0 0 0-.94-2.61c3.14-.35 6.44-1.54 6.44-7A5.44 5.44 0 0 0 20 4.77 5.07 5.07 0 0 0 19.91 1S18.73.65 16 2.48a13.38 13.38 0 0 0-7 0C6.27.65 5.09 1 5.09 1A5.07 5.07 0 0 0 5 4.77a5.44 5.44 0 0 0-1.5 3.78c0 5.42 3.3 6.61 6.44 7A3.37 3.37 0 0 0 9 18.13V22"/></svg>
          GitHub
        </a>
        
        
      </nav>
      <div class="header-tools">
        <button class="search-btn" aria-label="Search (⌘K)">
          <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="11" cy="11" r="8"/><line x1="21" y1="21" x2="16.65" y2="16.65"/></svg>
        </button>
        <button class="theme-toggle" aria-label="Toggle theme"></button>
        
        <div class="lang-selector">
          <button class="lang-btn" aria-label="Language">
            <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="12" cy="12" r="10"/><line x1="2" y1="12" x2="22" y2="12"/><path d="M12 2a15.3 15.3 0 0 1 4 10 15.3 15.3 0 0 1-4 10 15.3 15.3 0 0 1-4-10 15.3 15.3 0 0 1 4-10z"/></svg>
            JA
          </button>
          <ul class="lang-popup">
            
            <li><a href="#" data-lang="en">EN</a></li>
            
            <li><a href="#" data-lang="ja">JA</a></li>
            
          </ul>
        </div>
        
      </div>
      <button class="sidebar-toggle" aria-label="Menu">&#9776;</button>
    </div>
  </header>

  

  <div class="layout has-sidebar">
    
<aside class="sidebar">
  <nav class="sidebar-nav">
    
    <div class="nav-section">
      <a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;" class="nav-section-title active">A Tour of cpp-httplib</a>
      
      <ul class="nav-list">
        
        <li><a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;01-getting-started&#x2F;" class="">Getting Started</a></li>
        
        <li><a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;02-basic-client&#x2F;" class="active">Basic Client</a></li>
        
        <li><a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;03-basic-server&#x2F;" class="">Basic Server</a></li>
        
        <li><a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;04-static-file-server&#x2F;" class="">Static File Server</a></li>
        
        <li><a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;05-tls-setup&#x2F;" class="">TLS Setup</a></li>
        
        <li><a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;06-https-client&#x2F;" class="">HTTPS Client</a></li>
        
        <li><a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;07-https-server&#x2F;" class="">HTTPS Server</a></li>
        
        <li><a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;08-websocket&#x2F;" class="">WebSocket</a></li>
        
        <li><a href="&#x2F;cpp-httplib&#x2F;ja&#x2F;tour&#x2F;09-whats-next&#x2F;" class="">What&#x27;s Next</a></li>
        
      </ul>
      
    </div>
    
  </nav>
</aside>
<main class="content">
  <article>
    <h1>Basic Client</h1>
    <p>cpp-httplibはサーバーだけでなく、HTTPクライアント機能も備えています。<code>httplib::Client</code> を使って、GETやPOSTリクエストを送ってみましょう。</p>
<h2>テスト用サーバーの準備</h2>
<p>クライアントの動作を確認するために、リクエストを受け付けるサーバーを用意します。次のコードを保存し、前章と同じ手順でコンパイル・実行してください。サーバーの詳しい解説は次章で行います。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">#include </span><span style="color:#c0c5ce;">&quot;</span><span style="color:#a3be8c;">httplib.h</span><span style="color:#c0c5ce;">&quot;
</span><span style="color:#b48ead;">#include </span><span style="color:#c0c5ce;">&lt;</span><span style="color:#a3be8c;">iostream</span><span style="color:#c0c5ce;">&gt;
</span><span style="color:#c0c5ce;">
</span><span style="color:#b48ead;">int </span><span style="color:#8fa1b3;">main</span><span style="color:#c0c5ce;">() {
</span><span style="color:#c0c5ce;">    httplib::Server svr;
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    svr.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/hi</span><span style="color:#c0c5ce;">&quot;, [](</span><span style="color:#b48ead;">const auto </span><span style="color:#c0c5ce;">&amp;, </span><span style="color:#b48ead;">auto </span><span style="color:#c0c5ce;">&amp;res) {
</span><span style="color:#c0c5ce;">        res.</span><span style="color:#8fa1b3;">set_content</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">Hello!</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">text/plain</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">    });
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    svr.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/search</span><span style="color:#c0c5ce;">&quot;, [](</span><span style="color:#b48ead;">const auto </span><span style="color:#c0c5ce;">&amp;req, </span><span style="color:#b48ead;">auto </span><span style="color:#c0c5ce;">&amp;res) {
</span><span style="color:#c0c5ce;">        </span><span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> q = req.</span><span style="color:#8fa1b3;">get_param_value</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">q</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">        res.</span><span style="color:#8fa1b3;">set_content</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">Query: </span><span style="color:#c0c5ce;">&quot; + q, &quot;</span><span style="color:#a3be8c;">text/plain</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">    });
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    svr.</span><span style="color:#8fa1b3;">Post</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/post</span><span style="color:#c0c5ce;">&quot;, [](</span><span style="color:#b48ead;">const auto </span><span style="color:#c0c5ce;">&amp;req, </span><span style="color:#b48ead;">auto </span><span style="color:#c0c5ce;">&amp;res) {
</span><span style="color:#c0c5ce;">        res.</span><span style="color:#8fa1b3;">set_content</span><span style="color:#c0c5ce;">(req.</span><span style="color:#bf616a;">body</span><span style="color:#c0c5ce;">, &quot;</span><span style="color:#a3be8c;">text/plain</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">    });
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    svr.</span><span style="color:#8fa1b3;">Post</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/submit</span><span style="color:#c0c5ce;">&quot;, [](</span><span style="color:#b48ead;">const auto </span><span style="color:#c0c5ce;">&amp;req, </span><span style="color:#b48ead;">auto </span><span style="color:#c0c5ce;">&amp;res) {
</span><span style="color:#c0c5ce;">        std::string result;
</span><span style="color:#c0c5ce;">        </span><span style="color:#b48ead;">for </span><span style="color:#c0c5ce;">(</span><span style="color:#b48ead;">auto </span><span style="color:#c0c5ce;">&amp;[key, val] : req.</span><span style="color:#bf616a;">params</span><span style="color:#c0c5ce;">) {
</span><span style="color:#c0c5ce;">            result += key + &quot;</span><span style="color:#a3be8c;"> = </span><span style="color:#c0c5ce;">&quot; + val + &quot;</span><span style="color:#96b5b4;">\n</span><span style="color:#c0c5ce;">&quot;;
</span><span style="color:#c0c5ce;">        }
</span><span style="color:#c0c5ce;">        res.</span><span style="color:#8fa1b3;">set_content</span><span style="color:#c0c5ce;">(result, &quot;</span><span style="color:#a3be8c;">text/plain</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">    });
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    svr.</span><span style="color:#8fa1b3;">Post</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/upload</span><span style="color:#c0c5ce;">&quot;, [](</span><span style="color:#b48ead;">const auto </span><span style="color:#c0c5ce;">&amp;req, </span><span style="color:#b48ead;">auto </span><span style="color:#c0c5ce;">&amp;res) {
</span><span style="color:#c0c5ce;">        </span><span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> f = req.</span><span style="color:#bf616a;">form</span><span style="color:#c0c5ce;">.</span><span style="color:#8fa1b3;">get_file</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">file</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">        </span><span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> content = f.</span><span style="color:#bf616a;">filename </span><span style="color:#c0c5ce;">+ &quot;</span><span style="color:#a3be8c;"> (</span><span style="color:#c0c5ce;">&quot; + </span><span style="color:#8fa1b3;">std::to_string</span><span style="color:#c0c5ce;">(f.</span><span style="color:#bf616a;">content</span><span style="color:#c0c5ce;">.</span><span style="color:#8fa1b3;">size</span><span style="color:#c0c5ce;">()) + &quot;</span><span style="color:#a3be8c;"> bytes)</span><span style="color:#c0c5ce;">&quot;;
</span><span style="color:#c0c5ce;">        res.</span><span style="color:#8fa1b3;">set_content</span><span style="color:#c0c5ce;">(content, &quot;</span><span style="color:#a3be8c;">text/plain</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">    });
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    svr.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/users/:id</span><span style="color:#c0c5ce;">&quot;, [](</span><span style="color:#b48ead;">const auto </span><span style="color:#c0c5ce;">&amp;req, </span><span style="color:#b48ead;">auto </span><span style="color:#c0c5ce;">&amp;res) {
</span><span style="color:#c0c5ce;">        </span><span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> id = req.</span><span style="color:#bf616a;">path_params</span><span style="color:#c0c5ce;">.</span><span style="color:#8fa1b3;">at</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">id</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">        res.</span><span style="color:#8fa1b3;">set_content</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">User ID: </span><span style="color:#c0c5ce;">&quot; + id, &quot;</span><span style="color:#a3be8c;">text/plain</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">    });
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    svr.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(</span><span style="color:#b48ead;">R</span><span style="color:#c0c5ce;">&quot;(</span><span style="color:#a3be8c;">/files/(\d+)</span><span style="color:#c0c5ce;">)&quot;, [](</span><span style="color:#b48ead;">const auto </span><span style="color:#c0c5ce;">&amp;req, </span><span style="color:#b48ead;">auto </span><span style="color:#c0c5ce;">&amp;res) {
</span><span style="color:#c0c5ce;">        </span><span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> id = req.</span><span style="color:#bf616a;">matches</span><span style="color:#c0c5ce;">[</span><span style="color:#d08770;">1</span><span style="color:#c0c5ce;">];
</span><span style="color:#c0c5ce;">        res.</span><span style="color:#8fa1b3;">set_content</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">File ID: </span><span style="color:#c0c5ce;">&quot; + </span><span style="color:#8fa1b3;">std::string</span><span style="color:#c0c5ce;">(id), &quot;</span><span style="color:#a3be8c;">text/plain</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">    });
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; &quot;</span><span style="color:#a3be8c;">Listening on port 8080...</span><span style="color:#c0c5ce;">&quot; &lt;&lt; std::endl;
</span><span style="color:#c0c5ce;">    svr.</span><span style="color:#8fa1b3;">listen</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">0.0.0.0</span><span style="color:#c0c5ce;">&quot;, </span><span style="color:#d08770;">8080</span><span style="color:#c0c5ce;">);
</span><span style="color:#c0c5ce;">}
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">#include </span><span style="color:#183691;">&quot;httplib.h&quot;
</span><span style="font-weight:bold;color:#a71d5d;">#include </span><span style="color:#183691;">&lt;iostream&gt;
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">int </span><span style="font-weight:bold;color:#795da3;">main</span><span style="color:#323232;">() {
</span><span style="color:#323232;">    httplib::Server svr;
</span><span style="color:#323232;">
</span><span style="color:#323232;">    svr.Get(</span><span style="color:#183691;">&quot;/hi&quot;</span><span style="color:#323232;">, [](</span><span style="font-weight:bold;color:#a71d5d;">const auto &amp;</span><span style="color:#323232;">, </span><span style="font-weight:bold;color:#a71d5d;">auto &amp;</span><span style="color:#323232;">res) {
</span><span style="color:#323232;">        res.set_content(</span><span style="color:#183691;">&quot;Hello!&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;text/plain&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">    });
</span><span style="color:#323232;">
</span><span style="color:#323232;">    svr.Get(</span><span style="color:#183691;">&quot;/search&quot;</span><span style="color:#323232;">, [](</span><span style="font-weight:bold;color:#a71d5d;">const auto &amp;</span><span style="color:#323232;">req, </span><span style="font-weight:bold;color:#a71d5d;">auto &amp;</span><span style="color:#323232;">res) {
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> q </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> req.get_param_value(</span><span style="color:#183691;">&quot;q&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">        res.set_content(</span><span style="color:#183691;">&quot;Query: &quot; </span><span style="font-weight:bold;color:#a71d5d;">+</span><span style="color:#323232;"> q, </span><span style="color:#183691;">&quot;text/plain&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">    });
</span><span style="color:#323232;">
</span><span style="color:#323232;">    svr.Post(</span><span style="color:#183691;">&quot;/post&quot;</span><span style="color:#323232;">, [](</span><span style="font-weight:bold;color:#a71d5d;">const auto &amp;</span><span style="color:#323232;">req, </span><span style="font-weight:bold;color:#a71d5d;">auto &amp;</span><span style="color:#323232;">res) {
</span><span style="color:#323232;">        res.set_content(req.body, </span><span style="color:#183691;">&quot;text/plain&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">    });
</span><span style="color:#323232;">
</span><span style="color:#323232;">    svr.Post(</span><span style="color:#183691;">&quot;/submit&quot;</span><span style="color:#323232;">, [](</span><span style="font-weight:bold;color:#a71d5d;">const auto &amp;</span><span style="color:#323232;">req, </span><span style="font-weight:bold;color:#a71d5d;">auto &amp;</span><span style="color:#323232;">res) {
</span><span style="color:#323232;">        std::string result;
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">for </span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">auto &amp;</span><span style="color:#323232;">[key, val] </span><span style="font-weight:bold;color:#a71d5d;">:</span><span style="color:#323232;"> req.params) {
</span><span style="color:#323232;">            result </span><span style="font-weight:bold;color:#a71d5d;">+=</span><span style="color:#323232;"> key </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#183691;">&quot; = &quot; </span><span style="font-weight:bold;color:#a71d5d;">+</span><span style="color:#323232;"> val </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#183691;">&quot;</span><span style="color:#0086b3;">\n</span><span style="color:#183691;">&quot;</span><span style="color:#323232;">;
</span><span style="color:#323232;">        }
</span><span style="color:#323232;">        res.set_content(result, </span><span style="color:#183691;">&quot;text/plain&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">    });
</span><span style="color:#323232;">
</span><span style="color:#323232;">    svr.Post(</span><span style="color:#183691;">&quot;/upload&quot;</span><span style="color:#323232;">, [](</span><span style="font-weight:bold;color:#a71d5d;">const auto &amp;</span><span style="color:#323232;">req, </span><span style="font-weight:bold;color:#a71d5d;">auto &amp;</span><span style="color:#323232;">res) {
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> f </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> req.form.get_file(</span><span style="color:#183691;">&quot;file&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> content </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> f.filename </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#183691;">&quot; (&quot; </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#323232;">std::to_string(f.content.size()) </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#183691;">&quot; bytes)&quot;</span><span style="color:#323232;">;
</span><span style="color:#323232;">        res.set_content(content, </span><span style="color:#183691;">&quot;text/plain&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">    });
</span><span style="color:#323232;">
</span><span style="color:#323232;">    svr.Get(</span><span style="color:#183691;">&quot;/users/:id&quot;</span><span style="color:#323232;">, [](</span><span style="font-weight:bold;color:#a71d5d;">const auto &amp;</span><span style="color:#323232;">req, </span><span style="font-weight:bold;color:#a71d5d;">auto &amp;</span><span style="color:#323232;">res) {
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> id </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> req.path_params.at(</span><span style="color:#183691;">&quot;id&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">        res.set_content(</span><span style="color:#183691;">&quot;User ID: &quot; </span><span style="font-weight:bold;color:#a71d5d;">+</span><span style="color:#323232;"> id, </span><span style="color:#183691;">&quot;text/plain&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">    });
</span><span style="color:#323232;">
</span><span style="color:#323232;">    svr.Get(</span><span style="font-weight:bold;color:#a71d5d;">R</span><span style="color:#183691;">&quot;(/files/(\d+))&quot;</span><span style="color:#323232;">, [](</span><span style="font-weight:bold;color:#a71d5d;">const auto &amp;</span><span style="color:#323232;">req, </span><span style="font-weight:bold;color:#a71d5d;">auto &amp;</span><span style="color:#323232;">res) {
</span><span style="color:#323232;">        </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> id </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> req.matches[</span><span style="color:#0086b3;">1</span><span style="color:#323232;">];
</span><span style="color:#323232;">        res.set_content(</span><span style="color:#183691;">&quot;File ID: &quot; </span><span style="font-weight:bold;color:#a71d5d;">+ </span><span style="color:#323232;">std::string(id), </span><span style="color:#183691;">&quot;text/plain&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">    });
</span><span style="color:#323232;">
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt; </span><span style="color:#183691;">&quot;Listening on port 8080...&quot; </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;
</span><span style="color:#323232;">    svr.listen(</span><span style="color:#183691;">&quot;0.0.0.0&quot;</span><span style="color:#323232;">, </span><span style="color:#0086b3;">8080</span><span style="color:#323232;">);
</span><span style="color:#323232;">}
</span></pre>
</div></div>
<h2>GETリクエスト</h2>
<p>サーバーが起動したら、別のターミナルを開いて試してみましょう。まず、最もシンプルなGETリクエストです。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">#include </span><span style="color:#c0c5ce;">&quot;</span><span style="color:#a3be8c;">httplib.h</span><span style="color:#c0c5ce;">&quot;
</span><span style="color:#b48ead;">#include </span><span style="color:#c0c5ce;">&lt;</span><span style="color:#a3be8c;">iostream</span><span style="color:#c0c5ce;">&gt;
</span><span style="color:#c0c5ce;">
</span><span style="color:#b48ead;">int </span><span style="color:#8fa1b3;">main</span><span style="color:#c0c5ce;">() {
</span><span style="color:#c0c5ce;">    httplib::Client </span><span style="color:#8fa1b3;">cli</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">http://localhost:8080</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    </span><span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/hi</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">    </span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(res) {
</span><span style="color:#c0c5ce;">        std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">status </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;  </span><span style="color:#65737e;">// 200
</span><span style="color:#c0c5ce;">        std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">body </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;    </span><span style="color:#65737e;">// Hello!
</span><span style="color:#c0c5ce;">    }
</span><span style="color:#c0c5ce;">}
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">#include </span><span style="color:#183691;">&quot;httplib.h&quot;
</span><span style="font-weight:bold;color:#a71d5d;">#include </span><span style="color:#183691;">&lt;iostream&gt;
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">int </span><span style="font-weight:bold;color:#795da3;">main</span><span style="color:#323232;">() {
</span><span style="color:#323232;">    httplib::Client cli(</span><span style="color:#183691;">&quot;http://localhost:8080&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/hi&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
</span><span style="color:#323232;">        std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;status </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;  </span><span style="font-style:italic;color:#969896;">// 200
</span><span style="color:#323232;">        std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;    </span><span style="font-style:italic;color:#969896;">// Hello!
</span><span style="color:#323232;">    }
</span><span style="color:#323232;">}
</span></pre>
</div></div>
<p><code>httplib::Client</code> のコンストラクターにサーバーのアドレスを渡し、<code>Get()</code> でリクエストを送ります。戻り値の <code>res</code> からステータスコードやボディを取得できます。</p>
<p>対応する <code>curl</code> コマンドはこうなります。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#8fa1b3;">curl</span><span style="color:#c0c5ce;"> http://localhost:8080/hi
</span><span style="color:#65737e;"># Hello!
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="color:#323232;">curl http://localhost:8080/hi
</span><span style="font-style:italic;color:#969896;"># Hello!
</span></pre>
</div></div>
<h2>レスポンスの確認</h2>
<p>レスポンスには、ステータスコードとボディ以外にもヘッダー情報が含まれています。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/hi</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(res) {
</span><span style="color:#c0c5ce;">    </span><span style="color:#65737e;">// ステータスコード
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">status </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;  </span><span style="color:#65737e;">// 200
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    </span><span style="color:#65737e;">// ボディ
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">body </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;  </span><span style="color:#65737e;">// Hello!
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">    </span><span style="color:#65737e;">// ヘッダー
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#8fa1b3;">get_header_value</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">Content-Type</span><span style="color:#c0c5ce;">&quot;) &lt;&lt; std::endl;  </span><span style="color:#65737e;">// text/plain
</span><span style="color:#c0c5ce;">}
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/hi&quot;</span><span style="color:#323232;">);
</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
</span><span style="color:#323232;">    </span><span style="font-style:italic;color:#969896;">// ステータスコード
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;status </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;  </span><span style="font-style:italic;color:#969896;">// 200
</span><span style="color:#323232;">
</span><span style="color:#323232;">    </span><span style="font-style:italic;color:#969896;">// ボディ
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;  </span><span style="font-style:italic;color:#969896;">// Hello!
</span><span style="color:#323232;">
</span><span style="color:#323232;">    </span><span style="font-style:italic;color:#969896;">// ヘッダー
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;get_header_value(</span><span style="color:#183691;">&quot;Content-Type&quot;</span><span style="color:#323232;">) </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;  </span><span style="font-style:italic;color:#969896;">// text/plain
</span><span style="color:#323232;">}
</span></pre>
</div></div>
<p><code>res-&gt;body</code> は <code>std::string</code> なので、JSON レスポンスをパースしたい場合は <a href="https://github.com/nlohmann/json">nlohmann/json</a> などの JSON ライブラリにそのまま渡せます。</p>
<h2>クエリパラメーター</h2>
<p>GETリクエストにクエリパラメーターを付けるには、URLに直接書くか、<code>httplib::Params</code> を使います。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/search</span><span style="color:#c0c5ce;">&quot;, httplib::Params{{&quot;</span><span style="color:#a3be8c;">q</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">cpp-httplib</span><span style="color:#c0c5ce;">&quot;}});
</span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(res) {
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">body </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;  </span><span style="color:#65737e;">// Query: cpp-httplib
</span><span style="color:#c0c5ce;">}
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/search&quot;</span><span style="color:#323232;">, httplib::Params{{</span><span style="color:#183691;">&quot;q&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;cpp-httplib&quot;</span><span style="color:#323232;">}});
</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;  </span><span style="font-style:italic;color:#969896;">// Query: cpp-httplib
</span><span style="color:#323232;">}
</span></pre>
</div></div>
<p><code>httplib::Params</code> を使うと、特殊文字のURLエンコードを自動で行ってくれます。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#8fa1b3;">curl </span><span style="color:#c0c5ce;">&quot;</span><span style="color:#a3be8c;">http://localhost:8080/search?q=cpp-httplib</span><span style="color:#c0c5ce;">&quot;
</span><span style="color:#65737e;"># Query: cpp-httplib
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="color:#323232;">curl </span><span style="color:#183691;">&quot;http://localhost:8080/search?q=cpp-httplib&quot;
</span><span style="font-style:italic;color:#969896;"># Query: cpp-httplib
</span></pre>
</div></div>
<h2>パスパラメーター</h2>
<p>URLのパスに値を直接埋め込む場合も、クライアント側は特別なAPIは不要です。パスをそのまま <code>Get()</code> に渡すだけです。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/users/42</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(res) {
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">body </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;  </span><span style="color:#65737e;">// User ID: 42
</span><span style="color:#c0c5ce;">}
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/users/42&quot;</span><span style="color:#323232;">);
</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;  </span><span style="font-style:italic;color:#969896;">// User ID: 42
</span><span style="color:#323232;">}
</span></pre>
</div></div><div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#8fa1b3;">curl</span><span style="color:#c0c5ce;"> http://localhost:8080/users/42
</span><span style="color:#65737e;"># User ID: 42
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="color:#323232;">curl http://localhost:8080/users/42
</span><span style="font-style:italic;color:#969896;"># User ID: 42
</span></pre>
</div></div>
<p>テスト用サーバーには、正規表現でIDを数字のみに絞った <code>/files/(\d+)</code> もあります。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/files/42</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(res) {
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">body </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;  </span><span style="color:#65737e;">// File ID: 42
</span><span style="color:#c0c5ce;">}
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/files/42&quot;</span><span style="color:#323232;">);
</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;  </span><span style="font-style:italic;color:#969896;">// File ID: 42
</span><span style="color:#323232;">}
</span></pre>
</div></div><div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#8fa1b3;">curl</span><span style="color:#c0c5ce;"> http://localhost:8080/files/42
</span><span style="color:#65737e;"># File ID: 42
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="color:#323232;">curl http://localhost:8080/files/42
</span><span style="font-style:italic;color:#969896;"># File ID: 42
</span></pre>
</div></div>
<p><code>/files/abc</code> のように数字以外を渡すと404が返ります。仕組みは次章で解説します。</p>
<h2>リクエストヘッダー</h2>
<p>カスタムHTTPヘッダーを付けるには、<code>httplib::Headers</code> を渡します。<code>Get()</code> や <code>Post()</code> のどちらでも使えます。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/hi</span><span style="color:#c0c5ce;">&quot;, httplib::Headers{
</span><span style="color:#c0c5ce;">    {&quot;</span><span style="color:#a3be8c;">Authorization</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">Bearer my-token</span><span style="color:#c0c5ce;">&quot;}
</span><span style="color:#c0c5ce;">});
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/hi&quot;</span><span style="color:#323232;">, httplib::Headers{
</span><span style="color:#323232;">    {</span><span style="color:#183691;">&quot;Authorization&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;Bearer my-token&quot;</span><span style="color:#323232;">}
</span><span style="color:#323232;">});
</span></pre>
</div></div><div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#8fa1b3;">curl</span><span style="color:#bf616a;"> -H </span><span style="color:#c0c5ce;">&quot;</span><span style="color:#a3be8c;">Authorization: Bearer my-token</span><span style="color:#c0c5ce;">&quot; http://localhost:8080/hi
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="color:#323232;">curl -H </span><span style="color:#183691;">&quot;Authorization: Bearer my-token&quot;</span><span style="color:#323232;"> http://localhost:8080/hi
</span></pre>
</div></div>
<h2>POSTリクエスト</h2>
<p>テキストデータをPOSTしてみましょう。<code>Post()</code> の第2引数にボディ、第3引数にContent-Typeを指定します。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Post</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/post</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">Hello, Server!</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">text/plain</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(res) {
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">status </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;  </span><span style="color:#65737e;">// 200
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">body </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;    </span><span style="color:#65737e;">// Hello, Server!
</span><span style="color:#c0c5ce;">}
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Post(</span><span style="color:#183691;">&quot;/post&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;Hello, Server!&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;text/plain&quot;</span><span style="color:#323232;">);
</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;status </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;  </span><span style="font-style:italic;color:#969896;">// 200
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;    </span><span style="font-style:italic;color:#969896;">// Hello, Server!
</span><span style="color:#323232;">}
</span></pre>
</div></div>
<p>テスト用サーバーの <code>/post</code> はボディをそのまま返すので、送った文字列がそのまま返ってきます。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#8fa1b3;">curl</span><span style="color:#bf616a;"> -X</span><span style="color:#c0c5ce;"> POST</span><span style="color:#bf616a;"> -H </span><span style="color:#c0c5ce;">&quot;</span><span style="color:#a3be8c;">Content-Type: text/plain</span><span style="color:#c0c5ce;">&quot;</span><span style="color:#bf616a;"> -d </span><span style="color:#c0c5ce;">&quot;</span><span style="color:#a3be8c;">Hello, Server!</span><span style="color:#c0c5ce;">&quot; http://localhost:8080/post
</span><span style="color:#65737e;"># Hello, Server!
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="color:#323232;">curl -X POST -H </span><span style="color:#183691;">&quot;Content-Type: text/plain&quot;</span><span style="color:#323232;"> -d </span><span style="color:#183691;">&quot;Hello, Server!&quot;</span><span style="color:#323232;"> http://localhost:8080/post
</span><span style="font-style:italic;color:#969896;"># Hello, Server!
</span></pre>
</div></div>
<h2>フォームデータの送信</h2>
<p>HTMLフォームのように、キーと値のペアを送ることもできます。<code>httplib::Params</code> を使います。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Post</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/submit</span><span style="color:#c0c5ce;">&quot;, httplib::Params{
</span><span style="color:#c0c5ce;">    {&quot;</span><span style="color:#a3be8c;">name</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">Alice</span><span style="color:#c0c5ce;">&quot;},
</span><span style="color:#c0c5ce;">    {&quot;</span><span style="color:#a3be8c;">age</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">30</span><span style="color:#c0c5ce;">&quot;}
</span><span style="color:#c0c5ce;">});
</span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(res) {
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">body </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;
</span><span style="color:#c0c5ce;">    </span><span style="color:#65737e;">// age = 30
</span><span style="color:#c0c5ce;">    </span><span style="color:#65737e;">// name = Alice
</span><span style="color:#c0c5ce;">}
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Post(</span><span style="color:#183691;">&quot;/submit&quot;</span><span style="color:#323232;">, httplib::Params{
</span><span style="color:#323232;">    {</span><span style="color:#183691;">&quot;name&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;Alice&quot;</span><span style="color:#323232;">},
</span><span style="color:#323232;">    {</span><span style="color:#183691;">&quot;age&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;30&quot;</span><span style="color:#323232;">}
</span><span style="color:#323232;">});
</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;
</span><span style="color:#323232;">    </span><span style="font-style:italic;color:#969896;">// age = 30
</span><span style="color:#323232;">    </span><span style="font-style:italic;color:#969896;">// name = Alice
</span><span style="color:#323232;">}
</span></pre>
</div></div>
<p>これは <code>application/x-www-form-urlencoded</code> 形式で送信されます。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#8fa1b3;">curl</span><span style="color:#bf616a;"> -X</span><span style="color:#c0c5ce;"> POST</span><span style="color:#bf616a;"> -d </span><span style="color:#c0c5ce;">&quot;</span><span style="color:#a3be8c;">name=Alice&amp;age=30</span><span style="color:#c0c5ce;">&quot; http://localhost:8080/submit
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="color:#323232;">curl -X POST -d </span><span style="color:#183691;">&quot;name=Alice&amp;age=30&quot;</span><span style="color:#323232;"> http://localhost:8080/submit
</span></pre>
</div></div>
<h2>ファイルのPOST</h2>
<p>ファイルをアップロードするには、<code>httplib::UploadFormDataItems</code> を使ってマルチパートフォームデータとして送信します。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Post</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/upload</span><span style="color:#c0c5ce;">&quot;, httplib::UploadFormDataItems{
</span><span style="color:#c0c5ce;">    {&quot;</span><span style="color:#a3be8c;">file</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">Hello, File!</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">hello.txt</span><span style="color:#c0c5ce;">&quot;, &quot;</span><span style="color:#a3be8c;">text/plain</span><span style="color:#c0c5ce;">&quot;}
</span><span style="color:#c0c5ce;">});
</span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(res) {
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">body </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;  </span><span style="color:#65737e;">// hello.txt (12 bytes)
</span><span style="color:#c0c5ce;">}
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Post(</span><span style="color:#183691;">&quot;/upload&quot;</span><span style="color:#323232;">, httplib::UploadFormDataItems{
</span><span style="color:#323232;">    {</span><span style="color:#183691;">&quot;file&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;Hello, File!&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;hello.txt&quot;</span><span style="color:#323232;">, </span><span style="color:#183691;">&quot;text/plain&quot;</span><span style="color:#323232;">}
</span><span style="color:#323232;">});
</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res) {
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;  </span><span style="font-style:italic;color:#969896;">// hello.txt (12 bytes)
</span><span style="color:#323232;">}
</span></pre>
</div></div>
<p><code>UploadFormDataItems</code> の各要素は <code>{name, content, filename, content_type}</code> の4つのフィールドで構成されます。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#8fa1b3;">curl</span><span style="color:#bf616a;"> -F </span><span style="color:#c0c5ce;">&quot;</span><span style="color:#a3be8c;">file=Hello, File!;filename=hello.txt;type=text/plain</span><span style="color:#c0c5ce;">&quot; http://localhost:8080/upload
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="color:#323232;">curl -F </span><span style="color:#183691;">&quot;file=Hello, File!;filename=hello.txt;type=text/plain&quot;</span><span style="color:#323232;"> http://localhost:8080/upload
</span></pre>
</div></div>
<h2>エラーハンドリング</h2>
<p>ネットワーク通信では、サーバーに接続できない場合があります。<code>res</code> が有効かどうかを必ず確認しましょう。</p>
<div class="code-block-wrapper"><div data-code-theme="dark"><pre style="background-color:#2b303b;">
<span style="color:#c0c5ce;">httplib::Client </span><span style="color:#8fa1b3;">cli</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">http://localhost:9999</span><span style="color:#c0c5ce;">&quot;);  </span><span style="color:#65737e;">// 存在しないポート
</span><span style="color:#b48ead;">auto</span><span style="color:#c0c5ce;"> res = cli.</span><span style="color:#8fa1b3;">Get</span><span style="color:#c0c5ce;">(&quot;</span><span style="color:#a3be8c;">/hi</span><span style="color:#c0c5ce;">&quot;);
</span><span style="color:#c0c5ce;">
</span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(!res) {
</span><span style="color:#c0c5ce;">    </span><span style="color:#65737e;">// 接続エラー
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; &quot;</span><span style="color:#a3be8c;">Error: </span><span style="color:#c0c5ce;">&quot; &lt;&lt; </span><span style="color:#8fa1b3;">httplib::to_string</span><span style="color:#c0c5ce;">(res.</span><span style="color:#8fa1b3;">error</span><span style="color:#c0c5ce;">()) &lt;&lt; std::endl;
</span><span style="color:#c0c5ce;">    </span><span style="color:#65737e;">// Error: Connection
</span><span style="color:#c0c5ce;">    </span><span style="color:#b48ead;">return </span><span style="color:#d08770;">1</span><span style="color:#c0c5ce;">;
</span><span style="color:#c0c5ce;">}
</span><span style="color:#c0c5ce;">
</span><span style="color:#65737e;">// ここに到達すればレスポンスを受信できている
</span><span style="color:#b48ead;">if </span><span style="color:#c0c5ce;">(res-&gt;</span><span style="color:#bf616a;">status </span><span style="color:#c0c5ce;">!= </span><span style="color:#d08770;">200</span><span style="color:#c0c5ce;">) {
</span><span style="color:#c0c5ce;">    std::cout &lt;&lt; &quot;</span><span style="color:#a3be8c;">HTTP Error: </span><span style="color:#c0c5ce;">&quot; &lt;&lt; res-&gt;</span><span style="color:#bf616a;">status </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;
</span><span style="color:#c0c5ce;">    </span><span style="color:#b48ead;">return </span><span style="color:#d08770;">1</span><span style="color:#c0c5ce;">;
</span><span style="color:#c0c5ce;">}
</span><span style="color:#c0c5ce;">
</span><span style="color:#c0c5ce;">std::cout &lt;&lt; res-&gt;</span><span style="color:#bf616a;">body </span><span style="color:#c0c5ce;">&lt;&lt; std::endl;
</span></pre>
</div><div data-code-theme="light"><pre style="background-color:#ffffff;">
<span style="color:#323232;">httplib::Client </span><span style="font-weight:bold;color:#795da3;">cli</span><span style="color:#323232;">(</span><span style="color:#183691;">&quot;http://localhost:9999&quot;</span><span style="color:#323232;">);  </span><span style="font-style:italic;color:#969896;">// 存在しないポート
</span><span style="font-weight:bold;color:#a71d5d;">auto</span><span style="color:#323232;"> res </span><span style="font-weight:bold;color:#a71d5d;">=</span><span style="color:#323232;"> cli.Get(</span><span style="color:#183691;">&quot;/hi&quot;</span><span style="color:#323232;">);
</span><span style="color:#323232;">
</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(</span><span style="font-weight:bold;color:#a71d5d;">!</span><span style="color:#323232;">res) {
</span><span style="color:#323232;">    </span><span style="font-style:italic;color:#969896;">// 接続エラー
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt; </span><span style="color:#183691;">&quot;Error: &quot; </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt; </span><span style="color:#323232;">httplib::to_string(res.error()) </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;
</span><span style="color:#323232;">    </span><span style="font-style:italic;color:#969896;">// Error: Connection
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#0086b3;">1</span><span style="color:#323232;">;
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="font-style:italic;color:#969896;">// ここに到達すればレスポンスを受信できている
</span><span style="font-weight:bold;color:#a71d5d;">if </span><span style="color:#323232;">(res-&gt;status </span><span style="font-weight:bold;color:#a71d5d;">!= </span><span style="color:#0086b3;">200</span><span style="color:#323232;">) {
</span><span style="color:#323232;">    std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt; </span><span style="color:#183691;">&quot;HTTP Error: &quot; </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;status </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;
</span><span style="color:#323232;">    </span><span style="font-weight:bold;color:#a71d5d;">return </span><span style="color:#0086b3;">1</span><span style="color:#323232;">;
</span><span style="color:#323232;">}
</span><span style="color:#323232;">
</span><span style="color:#323232;">std::cout </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> res-&gt;body </span><span style="font-weight:bold;color:#a71d5d;">&lt;&lt;</span><span style="color:#323232;"> std::endl;
</span></pre>
</div></div>
<p>エラーには2つのレベルがあります。</p>
<ul>
<li><strong>接続エラー</strong>: サーバーに到達できなかった場合。<code>res</code> が偽になり、<code>res.error()</code> でエラーの種類を取得できます</li>
<li><strong>HTTPエラー</strong>: サーバーからエラーステータス（404、500など）が返ってきた場合。<code>res</code> は真ですが、<code>res-&gt;status</code> を確認する必要があります</li>
</ul>
<h2>次のステップ</h2>
<p>クライアントからリクエストを送る方法がわかりました。次は、サーバー側をもっと詳しく見てみましょう。ルーティングやパスパラメータなど、サーバーの機能を掘り下げます。</p>
<p><strong>次:</strong> <a href="../03-basic-server">Basic Server</a></p>

  </article>
</main>

  </div>

  <footer class="footer">
    © 2026 Yuji Hirose. All rights reserved.
  </footer>

  <!-- Search modal -->
  <div class="search-overlay" id="search-overlay">
    <div class="search-modal">
      <div class="search-input-wrap">
        <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round"><circle cx="11" cy="11" r="8"/><line x1="21" y1="21" x2="16.65" y2="16.65"/></svg>
        <input type="text" id="search-input" placeholder="Search..." autocomplete="off" spellcheck="false">
        <kbd class="search-esc">ESC</kbd>
      </div>
      <ul class="search-results" id="search-results"></ul>
    </div>
  </div>

  <script src="&#x2F;cpp-httplib/js/main.js"></script>
</body>
</html>