How to use php to implement the function of Chinese verification code

This article mainly introduces the simple Chinese verification code function implemented by php, and analyzes the implementation steps and operation methods of the php Chinese verification code function in the form of examples, including graphic creation, coding operations, session Operation and other related skills, friends in need can refer to

This article describes the simple Chinese verification code function implemented by PHP. Share it with everyone for your reference, the details are as follows:

img.php

<?php
session_start();
/*for($i=0;$i<4;$i++) {
  $rand .= dechex(rand(1,15));
}
$_SESSION[check_pic] = $rand;
*/
$image = imagecreatetruecolor(100, 30);
$bg = imagecolorallocate($image, 0, 0, 0);
$color = imagecolorallocate($image, 255, 255, 255);
//imagestring($image, rand(1,6), rand(3,60), rand(3,15), $rand, $color);
for($i=0;$i<3;$i++) {
  $color2 = imagecolorallocate($image, rand(0,255), rand(0,255),rand(0,255));
  imageline($image, rand(0,100), 0, 100, 30, $color2);
}
//rand() ---->0-max 不大于100
for($i=0;$i<200;$i++) {
  imagesetpixel($image, rand()%100, rand()%30, $color2);
}
//$str = iconv("gbk", "utf-8", "中");
$str = "中国";
$_SESSION[check_pic] = $str;
//解决中文，页面本身为utf-8
$str = mb_convert_encoding($str, "html-entities","utf-8" );
//2:字体大小 3：倾斜角度 x , y 坐标
imagettftext($image, 12, 0, 20, 20, $color, &#39;MSYH.TTF&#39;, $str);
//输出图片
header("Content-type: image/jpeg;charset=utf-8");
imagejpeg($image);
/*修改eclipse的配置，可以使得eclipse的新建项目的默认编码直接为UTF-8
在菜单栏的
Window->Preferences->General->Workspace->Text file encoding
将其改为UFT-8即可。*/
?>

sub.php

<?php
  header("Content-type: text/html;charset=utf-8");
  session_start();
  if($_POST[check]) {
    if($_POST[check]==$_SESSION[check_pic]) {
      echo "验证码正确：".$_SESSION[check_pic];
    } else {
      echo "验证码错误：".$_SESSION[check_pic];
    }
  }
?>
<form action="" method="post">
  <img alt="" src="img.php"><br/>
  <input type="text" name="check"><br/>
  <input type="submit" value="提交">
</form>

The running effect diagram is as follows:

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