Use of verification code for PHP development verification code

Use of verification code

New form

<?php
 
 if(isset($_REQUEST['code']))
 {
     session_start();
     if (strtolower($_REQUEST['code'])==$_SESSION['code'])
     {
         header('Content-type: text/html; charset=UTF8');
         echo '<font color="#0000CC">输入正确</font>';
     }
     else{
         header('Content-type: text/html; charset=UTF8');
         echo '<font color="#CC0000"><b>输入错误</b></font>';
     }
     exit();
 }
 
 ?>
 <!DOCTYPE html>
 <html>
 <head>
     <meta charset="utf-8"/>
     <title>确认验证</title>
 </head>
 <body>
 <form method="post" action="form.php">
     <p>验证码图片：<img id="captcha_img" border="1" src="captcha-2.php?r=<?php echo rand();?>" width="100" height="30">
 
     </p>
     <p>请输入图片的内容：<input type="text" name="code" value=""/></p>
     <p><input type="submit" value="提交" style="padding:6px 20px;"></p>
 </form>
 </body>
 </html>

Code explanation:

<?php
 
 if(isset($_REQUEST['code']))
 {
     session_start();
     if (strtolower($_REQUEST['code'])==$_SESSION['code'])
     {
         header('Content-type: text/html; charset=UTF8');
         echo '<font color="#0000CC">输入正确</font>';
     }
     else{
         header('Content-type: text/html; charset=UTF8');
         echo '<font color="#CC0000"><b>输入错误</b></font>';
     }
     exit();
 }
 
 ?>
 <!DOCTYPE html>
 <html>
 <head>
     <meta charset="utf-8"/>
     <title>确认验证</title>
 </head>
 <body>
 <form method="post" action="form.php">
     <p>验证码图片：
         <img src="captcha-2.php" alt="验证码，看不清楚，换一张"
          onclick="this.src = this.src + '?' + new Date().getTime();" />
     </p>
     <p>请输入图片的内容：<input type="text" name="code" value=""/></p>
     <p><input type="submit" value="提交" style="padding:6px 20px;"></p>
 </form>
 </body>
 </html>

Make an html verification code verification page, pass the submitted value to the form.php file through post submission, and import the picture into captcha-2.php,

onclick="this.src = this.src + '?' + new Date().getTime()；

Every time you click Picture randomly generates a new picture.

<?php
 
 if(isset($_REQUEST['code']))
 {
     session_start();
     if (strtolower($_REQUEST['code'])==$_SESSION['code'])
     {
         header('Content-type: text/html; charset=UTF8');
         echo '<font color="#0000CC">输入正确</font>';
     }
     else{
         header('Content-type: text/html; charset=UTF8');
         echo '<font color="#CC0000"><b>输入错误</b></font>';
     }
     exit();
 }

php judgment, calling the verification information stored through SESSION, judging the user's original input and comparing it with the information stored on the server. If they are equal, the input is correct, if they are not equal, the input is incorrect.

Now the production of alphanumeric verification code is completed.

Continuing Learning

new file

<?php session_start(); $image = imagecreatetruecolor(100,30); $bgcolor = imagecolorallocate($image,255,255,255);//#FFFFFFFFFFFF imagefill($image,0,0,$bgcolor); $captch_code=""; for ($i=0;$i<4;$i++){ $fontsize = 6; $fontcolor = imagecolorallocate($image,rand(0,120),rand(0,120),rand(0,120)); $data='abcdefghijklmnopqrstuvwxyz1234567890'; $fontcontent=substr($data,rand(0,strlen($data)),1); $captch_code.="$fontcontent"; $x = ($i * 100/4)+rand(5,10); $y = rand(5,10); imagestring($image,$fontsize,$x,$y,$fontcontent,$fontcolor); } $_SESSION['code']=$captch_code; for($i=0;$i<200;$i++){ $pointcolor = imagecolorallocate($image,rand(50,200),rand(50,200),rand(50,200)); imagesetpixel($image,rand(1,99),rand(1,29),$pointcolor); } for($i=0;$i<5;$i++){ $linecolor = imagecolorallocate($image,rand(60,220),rand(60,220),rand(60,220)); imageline($image,rand(1,99),rand(1,29),rand(1,99),rand(1,29),$linecolor); } header('content-type: image/png'); imagepng($image); //销毁 imagedestroy($image); ?>

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Use of verification code for PHP development verification code

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