曹鹏讲解php实现加减法验证码。主要介绍了php实现的加减法验证码代码，可以使用10以内的加减法生成图片。
复制代码 代码如下:
<?php
/*图片验证码文件，加减计算方式*/
class ImageCode{
private $Jiashu = 0; //加数或者减数
private $JianShu = 0; //被加数或者被减数
private $YunSuan = ''; //运算符
private $DeShu = 0; //得数
private $String = ''; //字符串样式
private $Img; //图片对象
private $Width = 100; //图片宽度
private $Height = 50; //图片高度
private $Ttf = 'Num.ttf';//字体文件
private $Session = 'code'; //Session变量
private function JiaShu(){
header('Content-type:image/png');
$this -> Jiashu = rand(1, 10);
$this -> JianShu = rand(1, 10);
$this -> YunSuan= $this -> Jiashu > $this -> JianShu ? '-' : '+';
$this -> DeShu = $this -> Jiashu > $this -> JianShu ? $this -> Jiashu - $this -> JianShu : $this -> Jiashu + $this -> JianShu;
}
public function Show( $W = 100, $H = 50, $T = 'Num.ttf', $Code = 'code' ){
$this -> JiaShu();
$this -> String = $this -> Jiashu . $this -> YunSuan . $this -> JianShu . '= ? ';
$this -> Width = $W;
$this -> Height = $H;
$this -> Ttf = $T;
$this -> Session= $Code;
session_start();
$_SESSION[$this -> Session] = $this -> DeShu;
$this -> Images();
}
private function Images(){
$this -> Img = imagecreate($this -> Width, $this -> Height);
$background_color = imagecolorallocate ($this -> Img, 255, 255, 255);
imagecolortransparent($this -> Img, $background_color);
imagettftext($this -> Img, 14, 0, 1, 20, imagecolorallocate ($this -> Img, 0, 0, 0), $this -> Ttf, $this -> String );
$this -> EchoImages();
}
private function EchoImages(){
imagepng($this -> Img);
imagedestroy($this -> Img);
}
}
$ImageCode = new ImageCode;
$ImageCode -> Show(130, 35, 'Num.ttf', 'code');