我们现在在网站注册等地方经常会见到需要你输入验证码的请款，它就是将随机数字或符号以图片的形式展现在用户面前，并提供验证后才能使用相关功能。今天我们就介绍具体实现代码如下：
<ol class="dp-xml">
<li class="alt"><span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> </span></span></li>
<li class=""><span> </span></li>
<li class="alt"><span>class rndnum{ </span></li>
<li class=""><span> </span></li>
<li class="alt"><span>function rnd(){ </span></li>
<li class=""><span>srand((double)microtime()*1000000); </span></li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">rnd_number</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">array</font></span><span>( </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">1</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'1', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">2</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'2', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">3</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'3', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">4</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'4', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">5</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'5', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">6</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'6', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">7</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'7', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">8</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'8', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">9</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'9', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">10</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'a', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">11</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'b', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">12</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'c', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">13</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'d', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">14</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'e', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">15</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'f', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">16</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'g', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">17</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'h', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">18</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'i', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">19</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'j', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">20</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'k', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">21</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'l', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">22</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'m', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">23</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'n', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">24</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'o', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">25</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'p', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">26</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'q', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">27</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'r', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">28</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'s', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">29</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'t', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">30</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'u', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">31</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'v', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">32</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'w', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">33</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'x', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">34</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'y', </span>
</li>
<li class="">
<span></span><span class="attribute"><font color="#ff0000">35</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'z', </span>
</li>
<li class="alt">
<span></span><span class="attribute"><font color="#ff0000">36</font></span><span>=</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>'0' </span>
</li>
<li class=""><span>); </span></li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">result</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">array_rand</font></span><span>($rnd_number,6); </span>
</li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">j</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">count</font></span><span>($result); </span>
</li>
<li class="alt">
<span>for ($</span><span class="attribute"><font color="#ff0000">i</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">0</font></span><span>;$i</span><span class="tag"><strong><font color="#006699"></font></strong></span><span>$j;$i++) { </span>
</li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">re.</font></span><span>=$rnd_number[$result[$i]]; </span>
</li>
<li class="alt"><span>} </span></li>
<li class="">
<span>//$</span><span class="attribute"><font color="#ff0000">re</font></span><span>=$rnd_number[$result[1]].$rnd_number[$result[2]].$rnd_number[$result[3]].$rnd_number[$result[4]].$rnd_number[$result[5]].$rnd_number[$result[6]].$rnd_number[$result[7]]; </span>
</li>
<li class="alt"><span>//return array_keys($result); </span></li>
<li class=""><span>return $re; </span></li>
<li class="alt"><span>} </span></li>
<li class=""><span>} </span></li>
<li class="alt"><span>/*用法 </span></li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">rndnum</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">new</font></span><span> rndnum(); </span>
</li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">num</font></span><span>=$rndnum-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>rnd(); </span>
</li>
<li class=""><span>echo $num; </span></li>
<li class="alt"><span>*/ </span></li>
<li class="">
<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span>
</li>
</ol>
生成PHP图形验证码的图片，将随机数填充到里边:
<ol class="dp-xml">
<li class="alt"><span><strong><font color="#006699"><span class="tag"></span><span class="tag-name">php</span></font></strong><span> </span></span></li>
<li class=""><span> </span></li>
<li class="alt"><span>Header("Content-type: image/PNG"); </span></li>
<li class=""><span>require_once("rndnum.php"); </span></li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">rndnum</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">new</font></span><span> rndnum(); </span>
</li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">authnum</font></span><span>=$rndnum-</span><span class="tag"><strong><font color="#006699">></font></strong></span><span>rnd(); </span>
</li>
<li class="alt"><span>session_start(); </span></li>
<li class=""><span>$_SESSION["extrra_code"]=$authnum; </span></li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">im</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">imagecreate</font></span><span>(72,20); </span>
</li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">black</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">ImageColorAllocate</font></span><span>($im, 0,0,0); </span>
</li>
<li class="alt">
<span>$</span><span class="attribute"><font color="#ff0000">white</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">ImageColorAllocate</font></span><span>($im, 255,255,255); </span>
</li>
<li class="">
<span>$</span><span class="attribute"><font color="#ff0000">gray</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">ImageColorAllocate</font></span><span>($im, 200,200,200); </span>
</li>
<li class="alt"><span>imagefill($im,0,0,$gray); </span></li>
<li class=""><span>imagestring($im,5,10,3,$authnum,$black); </span></li>
<li class="alt">
<span>for($</span><span class="attribute"><font color="#ff0000">i</font></span><span>=</span><span class="attribute-value"><font color="#0000ff">0</font></span><span>;$i</span><strong><font color="#006699"><span class="tag"><span class="tag-name">200</span></span></font></strong><span>;$i++) //加入干扰象素 </span>
</li>
<li class=""><span>{ </span></li>
<li class="alt">
<span> $</span><span class="attribute"><font color="#ff0000">randcolor</font></span><span> = </span><span class="attribute-value"><font color="#0000ff">ImageColorallocate</font></span><span>($im,rand(0,255),rand(0,255),rand(0,255)); </span>
</li>
<li class=""><span> imagesetpixel($im, rand()%70 , rand()%30 , $randcolor); </span></li>
<li class="alt"><span>} </span></li>
<li class=""><span>ImagePNG($im); </span></li>
<li class="alt"><span>ImageDestroy($im); </span></li>
<li class="">
<span></span><span class="tag"><strong><font color="#006699">?></font></strong></span><span> </span>
</li>
</ol>
以上就是全部PHP图形验证码的实现代码，希望对大家有所帮助。
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