PHP generates image verification code and click switching code

This article mainly introduces the example of PHP generating image verification code, and also introduces the method to achieve the effect of clicking to switch (can't see clearly? Change one). Friends in need can refer to it

Here to take a look Effect:

Now let us take a look at the PHP code

<?php
 
session_start();
function random($len) {
    $srcstr = "1a2s3d4f5g6hj8k9qwertyupzxcvbnm";
    mt_srand();
    $strs = "";
    for ($i = 0; $i < $len; $i++) {
        $strs .= $srcstr[mt_rand(0, 30)];
    }
    return $strs;
}
 
//随机生成的字符串
$str = random(4); 
 
//验证码图片的宽度
$width  = 50;      
 
//验证码图片的高度
$height = 25;     
 
//声明需要创建的图层的图片格式
@ header("Content-Type:image/png");
 
//创建一个图层
$im = imagecreate($width, $height);
 
//背景色
$back = imagecolorallocate($im, 0xFF, 0xFF, 0xFF);
 
//模糊点颜色
$pix  = imagecolorallocate($im, 187, 230, 247);
 
//字体色
$font = imagecolorallocate($im, 41, 163, 238);
 
//绘模糊作用的点
mt_srand();
for ($i = 0; $i < 1000; $i++) {
    imagesetpixel($im, mt_rand(0, $width), mt_rand(0, $height), $pix);
}
 
//输出字符
imagestring($im, 5, 7, 5, $str, $font);
 
//输出矩形
imagerectangle($im, 0, 0, $width -1, $height -1, $font);
 
//输出图片
imagepng($im);
 
imagedestroy($im);
 
$str = md5($str);
 
//选择 cookie
//SetCookie("verification", $str, time() + 7200, "/");
 
//选择 Session
$_SESSION["verification"] = $str;
?>

Then just call it in the page:

<img id="checkpic" onclick="changing();" src=&#39;/images/checkcode.php&#39; />

If you want to achieve "cannot see Clear? Change one" effect, add the following JS to the page

function changing(){
    document.getElementById('checkpic').src="/images/checkcode.php?"+Math.random();
}

The above is the entire content of this article, I hope it will be helpful to everyone's learning, please pay attention to PHP for more related content Chinese website!

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