简单实例php验证码代码

<?php
session_start();
$string = null;
$im = imagecreatetruecolor(60, 25); //创建真彩图60*25
$bg = imagecolorallocate($im, 255, 255, 255); //白色背景
imagefill($im, 0, 0, $bg); //填充白色
$x = 5; //
$y = 0; //文字坐标
for ($i = 0; $i & lt; 4; $i++) {
    $char = mt_rand(0, 9);
    $string.= $char;
    $y = mt_rand(0, 10);
    $ccolor = imagecolorallocate($im, mt_rand(0, 230) , mt_rand(0, 230) , mt_rand(0, 230));
    imagechar($im, 6, $x, $y, $char, $ccolor); //填充文字
    $x+= mt_rand(10, 15);
}
for ($i = 0; $i{$x1 = mt_rand(0, 80); $x2 = mt_rand(0, 80); $y1 = mt_rand(0, 30); $y2 = mt_rand(0, 30); $x2 = $x1 + mt_rand(1, 5); $y2 = $y1 + mt_rand(1, 5); $lc = imagecolorallocate($im, mt_rand(0, 230) , mt_rand(0, 230) , mt_rand(0, 230)); imageline($im, $x1, $y1, $x2, $y2, $lc); //填充线条
}$_session['code'] = md5($string); header("content-type:image/jpeg"); imagepng($im); imagedestroy($im);