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    5. 

  5.   <title>Return an item from the argument list</title>
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  11.  <div class="up"><a href="ref.funchand.html">Function handling 函数</a></div>
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  12.  <div class="home"><a href="index.html">PHP Manual</a></div>
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  13. </div><hr /><div id="function.func-get-arg" class="refentry">
    14. 

  14.  <div class="refnamediv">
    15. 

  15.   <h1 class="refname">func_get_arg</h1>
    16. 

  16.   <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">func_get_arg</span> &mdash; <span class="dc-title">Return an item from the argument list</span></p>
    17. 

  17. 

  18.  </div>
    19. 

  19.  
    20. 

  20.  <div class="refsect1 description" id="refsect1-function.func-get-arg-description">
    21. 

  21.   <h3 class="title">说明</h3>
    22. 

  22.   <div class="methodsynopsis dc-description">
    23. 

  23.    <span class="type"><a href="language.pseudo-types.html#language.types.mixed" class="type mixed">mixed</a></span> <span class="methodname"><strong>func_get_arg</strong></span>
    24. 

  24.     ( <span class="methodparam"><span class="type">int</span> <code class="parameter">$arg_num</code></span>
    25. 

  25.    )</div>
    26. 

  26. 

  27.   <p class="para rdfs-comment">
    28. 

  28.    Gets the specified argument from a user-defined function&#039;s argument list.
    29. 

  29.   </p>
    30. 

  30.   <p class="para">
    31. 

  31.    This function may be used in conjunction with 
    32. 

  32.     <span class="function"><a href="function.func-get-args.html" class="function">func_get_args()</a></span> and  <span class="function"><a href="function.func-num-args.html" class="function">func_num_args()</a></span>
    33. 

  33.    to allow user-defined functions to accept variable-length argument lists.
    34. 

  34.   </p>
    35. 

  35.  </div>
    36. 

  36. 

  37. 

  38.  <div class="refsect1 parameters" id="refsect1-function.func-get-arg-parameters">
    39. 

  39.   <h3 class="title">参数</h3>
    40. 

  40.   <p class="para">
    41. 

  41.    <dl>
    42. 

  42. 

  43.     <dt>
    44. 

  44. 

  45.      <span class="term"><em><code class="parameter">arg_num</code></em></span>
    46. 

  46.      <dd>
    47. 

  47. 

  48.       <p class="para">
    49. 

  49.        The argument offset. Function arguments are counted starting from
    50. 

  50.        zero.
    51. 

  51.       </p>
    52. 

  52.      </dd>
    53. 

  53. 

  54.     </dt>
    55. 

  55. 

  56.    </dl>
    57. 

  57. 

  58.   </p>
    59. 

  59.  </div>
    60. 

  60. 

  61. 

  62.  <div class="refsect1 returnvalues" id="refsect1-function.func-get-arg-returnvalues">
    63. 

  63.   <h3 class="title">返回值</h3>
    64. 

  64.   <p class="para">
    65. 

  65.    Returns the specified argument, or <strong><code>FALSE</code></strong> on error.
    66. 

  66.   </p>
    67. 

  67.  </div>
    68. 

  68. 

  69. 

  70.  <div class="refsect1 changelog" id="refsect1-function.func-get-arg-changelog">
    71. 

  71.   <h3 class="title">更新日志</h3>
    72. 

  72.   <p class="para">
    73. 

  73.    <table class="doctable informaltable">
    74. 

  74.     
    75. 

  75.      <thead>
    76. 

  76.       <tr>
    77. 

  77.        <th>版本</th>
    78. 

  78.        <th>说明</th>
    79. 

  79.       </tr>
    80. 

  80. 

  81.      </thead>
    82. 

  82. 

  83.      <tbody class="tbody">
    84. 

  84.       <tr>
    85. 

  85.        <td>5.3.0</td>
    86. 

  86.        <td>
    87. 

  87.         This function can now be used in parameter lists.
    88. 

  88.        </td>
    89. 

  89.       </tr>
    90. 

  90. 

  91.       <tr>
    92. 

  92.        <td>5.3.0</td>
    93. 

  93.        <td>
    94. 

  94.         If this function is called from the outermost scope of a file
    95. 

  95.         which has been included by calling  <span class="function"><a href="function.include.html" class="function">include</a></span>
    96. 

  96.         or  <span class="function"><a href="function.require.html" class="function">require</a></span> from within a function in the
    97. 

  97.         calling file, it now generates a warning and returns <strong><code>FALSE</code></strong>.
    98. 

  98.        </td>
    99. 

  99.       </tr>
    100. 

  100. 

  101.      </tbody>
    102. 

  102.     
    103. 

  103.    </table>
    104. 

  104. 

  105.   </p>
    106. 

  106.  </div>
    107. 

  107. 

  108. 

  109.  <div class="refsect1 errors" id="refsect1-function.func-get-arg-errors">
    110. 

  110.   <h3 class="title">错误／异常</h3>
    111. 

  111.   <p class="para">
    112. 

  112.    Generates a warning if called from outside of a user-defined function, or
    113. 

  113.    if <em><code class="parameter">arg_num</code></em> is greater than the number of arguments
    114. 

  114.    actually passed.
    115. 

  115.   </p>
    116. 

  116.  </div>
    117. 

  117. 

  118. 

  119.  <div class="refsect1 examples" id="refsect1-function.func-get-arg-examples">
    120. 

  120.   <h3 class="title">范例</h3>
    121. 

  121.   <p class="para">
    122. 

  122.    <div class="example" id="example-4866">
    123. 

  123.     <p><strong>Example #1  <span class="function"><strong>func_get_arg()</strong></span> example</strong></p>
    124. 

  124.     <div class="example-contents">
    125. 

  125. <div class="phpcode"><code><span style="color: #000000">
    126. 

  126. <span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">function&nbsp;</span><span style="color: #0000BB">foo</span><span style="color: #007700">()<br />{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$numargs&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">func_num_args</span><span style="color: #007700">();<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"Number&nbsp;of&nbsp;arguments:&nbsp;</span><span style="color: #0000BB">$numargs</span><span style="color: #DD0000">&lt;br&nbsp;/&gt;\n"</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;if&nbsp;(</span><span style="color: #0000BB">$numargs&nbsp;</span><span style="color: #007700">&gt;=&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">"Second&nbsp;argument&nbsp;is:&nbsp;"&nbsp;</span><span style="color: #007700">.&nbsp;</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">)&nbsp;.&nbsp;</span><span style="color: #DD0000">"&lt;br&nbsp;/&gt;\n"</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;}<br />}<br /><br /></span><span style="color: #0000BB">foo&nbsp;</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">2</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">3</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
    127. 

  127. </span>
    128. 

  128. </code></div>
    129. 

  129.     </div>
    130. 

  130. 

  131.    </div>
    132. 

  132.   </p>
    133. 

  133.   <p class="para">
    134. 

  134.    <div class="example" id="example-4867">
    135. 

  135.     <p><strong>Example #2  <span class="function"><strong>func_get_arg()</strong></span> example before and
    136. 

  136.     after PHP 5.3</strong></p>
    137. 

  137.     <div class="example-contents">
    138. 

  138. <div class="phpcode"><code><span style="color: #000000">
    139. 

  139. test.php<br /><span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">function&nbsp;</span><span style="color: #0000BB">foo</span><span style="color: #007700">()&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;include&nbsp;</span><span style="color: #DD0000">'./fga.inc'</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">foo</span><span style="color: #007700">(</span><span style="color: #DD0000">'First&nbsp;arg'</span><span style="color: #007700">,&nbsp;</span><span style="color: #DD0000">'Second&nbsp;arg'</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;<br /></span><br />fga.php<br /><span style="color: #0000BB">&lt;?php<br /><br />$arg&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">$arg</span><span style="color: #007700">);<br /><br /></span><span style="color: #0000BB">?&gt;</span>
    140. 

  140. </span>
    141. 

  141. </code></div>
    142. 

  142.     </div>
    143. 

  143. 

  144.     <div class="example-contents"><p>
    145. 

  145.      Output previous to PHP 5.3:
    146. 

  146.     </p></div>
    147. 

  147.     <div class="example-contents screen">
    148. 

  148. <div class="cdata"><pre>
    149. 

  149. &#039;Second arg&#039;
    150. 

  150. </pre></div>
    151. 

  151.     </div>
    152. 

  152.     <div class="example-contents"><p>
    153. 

  153.      Output in PHP 5.3 and later:
    154. 

  154.     </p></div>
    155. 

  155.     <div class="example-contents screen">
    156. 

  156. <div class="cdata"><pre>
    157. 

  157. Warning: func_get_arg():  Called from the global scope - no function
    158. 

  158. context in /home/torben/Desktop/code/ml/fga.inc on line 3
    159. 

  159. false
    160. 

  160. </pre></div>
    161. 

  161.     </div>
    162. 

  162.    </div>
    163. 

  163.   </p>
    164. 

  164. 

  165.   <p class="para">
    166. 

  166.    <div class="example" id="example-4868">
    167. 

  167.     <p><strong>Example #3  <span class="function"><strong>func_get_arg()</strong></span> example of byref and byval arguments</strong></p>
    168. 

  168.     <div class="example-contents">
    169. 

  169. <div class="phpcode"><code><span style="color: #000000">
    170. 

  170. <span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">function&nbsp;</span><span style="color: #0000BB">byVal</span><span style="color: #007700">(</span><span style="color: #0000BB">$arg</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">'As&nbsp;passed&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;:&nbsp;'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">)),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$arg&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'baz'</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">'After&nbsp;change&nbsp;&nbsp;:&nbsp;'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">)),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br />}<br /><br />function&nbsp;</span><span style="color: #0000BB">byRef</span><span style="color: #007700">(&amp;</span><span style="color: #0000BB">$arg</span><span style="color: #007700">)&nbsp;{<br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">'As&nbsp;passed&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;:&nbsp;'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">)),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;</span><span style="color: #0000BB">$arg&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'baz'</span><span style="color: #007700">;<br />&nbsp;&nbsp;&nbsp;&nbsp;echo&nbsp;</span><span style="color: #DD0000">'After&nbsp;change&nbsp;&nbsp;:&nbsp;'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">var_export</span><span style="color: #007700">(</span><span style="color: #0000BB">func_get_arg</span><span style="color: #007700">(</span><span style="color: #0000BB">0</span><span style="color: #007700">)),&nbsp;</span><span style="color: #0000BB">PHP_EOL</span><span style="color: #007700">;<br />}<br /><br /></span><span style="color: #0000BB">$arg&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #DD0000">'bar'</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">byVal</span><span style="color: #007700">(</span><span style="color: #0000BB">$arg</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">byRef</span><span style="color: #007700">(</span><span style="color: #0000BB">$arg</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?&gt;</span>
    171. 

  171. </span>
    172. 

  172. </code></div>
    173. 

  173.     </div>
    174. 

  174. 

  175.      <div class="example-contents"><p>以上例程会输出：</p></div>
    176. 

  176.     <div class="example-contents screen"><br />
    177. 

  177. As passed     : &#039;bar&#039;<br />
    178. 

  178. After change  : &#039;bar&#039;<br />
    179. 

  179. As passed     : &#039;bar&#039;<br />
    180. 

  180. After change  : &#039;baz&#039;<br />
    181. 

  181.     </div>
    182. 

  182.    </div>
    183. 

  183.   </p>
    184. 

  184. 

  185.  </div>
    186. 

  186. 

  187. 

  188.  <div class="refsect1 notes" id="refsect1-function.func-get-arg-notes">
    189. 

  189.   <h3 class="title">注释</h3>
    190. 

  190.   <blockquote class="note"><p><strong class="note">Note</strong>: <p class="para">因为函数依赖于当前作用域以确定参数的细节，所以在
    191. 

  191. 5.3.0 以前的版本中不能用作函数的参数。如必须传递此值时，可将结果赋与一个变量，然后用此变量进行传递。</p></p></blockquote>
    192. 

  192.   <blockquote class="note"><p><strong class="note">Note</strong>: <p class="para">如果参数以引用方式传递，函数对该参数的任何改变将在函数返回后保留。</p></p></blockquote>
    193. 

  193.   <blockquote class="note"><p><strong class="note">Note</strong>: 
    194. 

  194.    <span class="simpara">
    195. 

  195.     This function returns a copy of the passed arguments only, and does not
    196. 

  196.     account for default (non-passed) arguments.
    197. 

  197.    </span>
    198. 

  198.   </p></blockquote>
    199. 

  199.  </div>
    200. 

  200. 

  201. 

  202.  <div class="refsect1 seealso" id="refsect1-function.func-get-arg-seealso">
    203. 

  203.   <h3 class="title">参见</h3>
    204. 

  204.   <p class="para">
    205. 

  205.    <ul class="simplelist">
    206. 

  206.     <li class="member"> <span class="function"><a href="function.func-get-args.html" class="function" rel="rdfs-seeAlso">func_get_args()</a> - Returns an array comprising a function's argument list</span></li>
    207. 

  207.     <li class="member"> <span class="function"><a href="function.func-num-args.html" class="function" rel="rdfs-seeAlso">func_num_args()</a> - Returns the number of arguments passed to the function</span></li>
    208. 

  208.    </ul>
    209. 

  209.   </p>
    210. 

  210.  </div>
    211. 

  211. 

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