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<div id="intlchar.isidstart" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">IntlChar::isIDStart</h1>
  <p class="verinfo">(PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">IntlChar::isIDStart</span> &mdash; <span class="dc-title">Check if code point is permissible as the first character in an identifier</span></p>

 </div>

 <div class="refsect1 description" id="refsect1-intlchar.isidstart-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="modifier">public</span> <span class="modifier">static</span> <span class="methodname"><strong>IntlChar::isIDStart</strong></span>(<span class="methodparam"><span class="type"><span class="type"><a href="language.types.integer.php" class="type int">int</a></span>|<span class="type"><a href="language.types.string.php" class="type string">string</a></span></span> <code class="parameter">$codepoint</code></span>): <span class="type"><span class="type"><a href="language.types.null.php" class="type null">?</a></span><span class="type"><a href="language.types.boolean.php" class="type bool">bool</a></span></span></div>

  <p class="para rdfs-comment">
   Determines if the specified character is permissible as the first character in an identifier according to Unicode (The Unicode Standard, Version 3.0, chapter 5.16 Identifiers).
  </p>
  <p class="para">
   <strong><code><a href="reserved.constants.php#constant.true">true</a></code></strong> for characters with general categories &quot;L&quot; (letters) and &quot;Nl&quot; (letter numbers).
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-intlchar.isidstart-parameters">
  <h3 class="title">参数</h3>
  <dl>
   
    <dt><code class="parameter">codepoint</code></dt>
    <dd>
     <p class="para">The <span class="type"><a href="language.types.integer.php" class="type int">int</a></span> codepoint value (e.g. <code class="literal">0x2603</code> for <em>U+2603 SNOWMAN</em>), or the character encoded as a UTF-8 <span class="type"><a href="language.types.string.php" class="type string">string</a></span> (e.g. <code class="literal">&quot;\u{2603}&quot;</code>)</p>
    </dd>
   
  </dl>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-intlchar.isidstart-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   Returns <strong><code><a href="reserved.constants.php#constant.true">true</a></code></strong> if
   <code class="parameter">codepoint</code> may start an identifier, <strong><code><a href="reserved.constants.php#constant.false">false</a></code></strong> if not. Returns <strong><code><a href="reserved.constants.php#constant.null">null</a></code></strong> on failure.
  </p>
 </div>


 <div class="refsect1 examples" id="refsect1-intlchar.isidstart-examples">
  <h3 class="title">示例</h3>
  <div class="example" id="example-2705">
   <p><strong>示例 #1 Testing different code points</strong></p>
   <div class="example-contents">
    <div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB">&lt;?php<br />var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">IntlChar</span><span style="color: #007700">::</span><span style="color: #0000BB">isIDStart</span><span style="color: #007700">(</span><span style="color: #DD0000">"A"</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">IntlChar</span><span style="color: #007700">::</span><span style="color: #0000BB">isIDStart</span><span style="color: #007700">(</span><span style="color: #DD0000">"$"</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">IntlChar</span><span style="color: #007700">::</span><span style="color: #0000BB">isIDStart</span><span style="color: #007700">(</span><span style="color: #DD0000">"\n"</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">IntlChar</span><span style="color: #007700">::</span><span style="color: #0000BB">isIDStart</span><span style="color: #007700">(</span><span style="color: #DD0000">"\u{2603}"</span><span style="color: #007700">));<br /></span><span style="color: #0000BB">?&gt;</span></span></code></div>
   </div>

   <div class="example-contents"><p>以上示例会输出：</p></div>
   <div class="example-contents screen">
    <div class="examplescode"><pre class="examplescode">bool(true)
bool(false)
bool(false)
bool(false)</pre>
</div>
   </div>
  </div>
 </div>


 <div class="refsect1 seealso" id="refsect1-intlchar.isidstart-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li><span class="function"><a href="intlchar.isalpha.php" class="function" rel="rdfs-seeAlso">IntlChar::isalpha()</a> - Check if code point is a letter character</span></li>
    <li><span class="function"><a href="intlchar.isidpart.php" class="function" rel="rdfs-seeAlso">IntlChar::isIDPart()</a> - Check if code point is permissible in an identifier</span></li>
    <li><strong><code><a href="class.intlchar.php#intlchar.constants.property-id-start">IntlChar::PROPERTY_ID_START</a></code></strong></li>
   </ul>
  </p>
 </div>


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