本文实例讲述了PHP生成图片验证码功能。分享给大家供大家参考，具体如下：

只是简单的用随机函数实现了图片的生成，没有对验证的整个流程做介绍。

代码如下：

<?php
/**
 * Created by JetBrains PhpStorm.
 * User: lee
 * To change this template use File | Settings | File Templates.
 */
header("content-type:image/png");
$validateLength=4;
$strToDraw="";
$chars=[
  "0","1","2","3","4",
  "5","6","7","8","9",
  "a","b","c","d","e","f","g",
  "h","i","j","k","l","m","n",
  "o","p","q","r","s","t",
  "u","v","w","x","y","z",
  "A","B","C","D","E","F","G",
  "H","I","J","K","L","M","N",
  "O","P","Q","R","S","T",
  "U","V","W","X","Y","Z"
];
$imgW=80;
$imgH=25;
$imgRes=imagecreate($imgW,$imgH);
$imgColor=imagecolorallocate($imgRes,255,255,100);
$color=imagecolorallocate($imgRes,0,0,0);
for($i=0;$i<$validateLength;$i++){
  $rand=rand(1,58);
  $strToDraw=$strToDraw." ".$chars[$rand];
}
imagestring($imgRes,5,0,5,$strToDraw,$color);
for($i=0;$i<100;$i++){
  imagesetpixel($imgRes,rand(0,$imgW),rand(0,$imgH),$color);
}
imagepng($imgRes);
imagedestroy($imgRes);

运行效果如下：

PS：这里再为大家推荐几款比较实用的图片处理工具供大家参考使用：

在线图片转换BASE64工具：
http://tools.gimoo.net/transcoding/img2base64

ICO图标在线生成工具：
http://tools.gimoo.net/aideddesign/ico_img

在线Email邮箱图标制作工具：
http://tools.gimoo.net/email/emaillogo

在线图片格式转换(jpg/bmp/gif/png)工具：
http://tools.gimoo.net/aideddesign/picext

更多关于PHP相关内容感兴趣的读者可查看本站专题：《PHP图形与图片操作技巧汇总》、《PHP基本语法入门教程》、《PHP运算与运算符用法总结》、《php面向对象程序设计入门教程》、《PHP网络编程技巧总结》、《PHP数组(Array)操作技巧大全》、《php字符串(string)用法总结》、《php+mysql数据库操作入门教程》及《php常见数据库操作技巧汇总》

希望本文所述对大家PHP程序设计有所帮助。