How to create a simple verification code in php

This article mainly shares with you how to create a simple verification code in PHP. I hope it can help you.

1. Create a verification code output file

session_start();

//5.创建一个验证码
$code_length = 4;
$codes = '';

for($i=0;$i<$code_length;$i++)
{
    $codes .= dechex(mt_rand(0,15));
}

//7.生成sesstion
$_SESSION[&#39;code&#39;] = $codes;

$width = 75;
$height = 25;

//1. 创建一张图片
$img = imagecreatetruecolor($width,$height);

//4. 创建图片静态内容
//白色
$white = imagecolorallocate($img, 255, 255, 255);
//黑色
$black = imagecolorallocate($img, 100, 100, 100);
//红色
$red = imagecolorallocate($img, 255, 0, 0);

//图片背景
imagefill($img, 0, 0, $white);


//随机线条
for($i=0;$i<4;$i++)
{
    //创建随机颜色
    $img_mt_color = imagecolorallocate($img, mt_rand(0,255), mt_rand(0,255), mt_rand(0,255));

    //画线
    imageline($img, mt_rand(0,$width),mt_rand(0,$height), mt_rand(0,$width),mt_rand(0,$height), $img_mt_color);
}

//随机打雪花
for($i=0;$i<100;$i++)
{
    //创建随机浅淡色
    $img_mt_color = imagecolorallocate($img, mt_rand(200,255), mt_rand(200,255), mt_rand(200,255));

    //画*
    imagestring($img,1, mt_rand(0,$width),mt_rand(0,$height),&#39;*&#39;,$img_mt_color);
}

//imagestring($img, 3, 10, 10, strlen($codes), $red);


//6.绘制验证码
for($i=0;$i<$code_length;$i++)
{
    //创建验证码颜色（偏深色）
    $img_mt_color = imagecolorallocate($img, mt_rand(0,100), mt_rand(0,150), mt_rand(0,200));
    //生成验证码每一位字符
    imagestring($img, mt_rand(3,5), $i*$width/4 + mt_rand(0,10), mt_rand(1,$height/2), $_SESSION[&#39;code&#39;][$i], $img_mt_color);
}

//创建红色矩形边框
imagerectangle($img, 0, 0, $width-1, $height-1, $red);

//2. 让浏览器知道输出的是一张图片
header(&#39;Content-type:image/png&#39;);
//3. 输出
imagepng($img);
//4. 销毁
imagedestroy($img);

2. Call this verification code on another page, And realize click refresh verification code:

<img src="php_code_img.php" id="myCodeImg" />

<script type="text/javascript">
(function(){
    var myCodeImg = document.getElementById_x(&#39;myCodeImg&#39;);
    myCodeImg.onclick = function()
    {
        this.src = &#39;./php_code_img.php?mt=&#39;+Math.ceil(Math.random()*1000);
    }
})();
</script>

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