How to implement color-changing verification code in PHP

This article mainly introduces the method of implementing color-changing verification code in PHP. It has certain reference value. Now I share it with you. Friends in need can refer to it.

Verification code must have been seen by everyone. Come on, this article will introduce to you how to implement color-changing verification codes in PHP. Interested friends can refer to

<?php 
header("Content-type: image/png,charset=&#39;utf-8&#39;"); 
$im = imagecreatetruecolor(400, 30); 
//白色 
$white = imagecolorallocate($im, 255, 255, 255); 
//红色 
$red = imagecolorallocate($im, 255, 0, 0); 
//黑色 
$black=imagecolorallocate($im, 0, 0, 0); 
//绿色 
$green=imagecolorallocate($im, 0, 255, 0); 
//蓝色 
$blue=imagecolorallocate($im, 0, 0, 255); 
$color_arr=array($green,$blue,$red); 
$color=array_rand($color_arr); 
$text = &#39;我靠这验证码太变态啦&#39;; 
$textlen=iconv_strlen($text,&#39;utf-8&#39;);//计算字符串长度 
//随机截取两个字符，变色显示 
$p1=rand(1,$textlen)-1; 
while(($p2=rand(1,$textlen)-1)==$p1); 
$w1=iconv_substr($text,$p1,1,&#39;utf-8&#39;); 
$w2=iconv_substr($text,$p1,1,&#39;utf-8&#39;); 
//字体文件 （PS：T不错的php Q扣峮：276167802，验证：csl） 
$font = &#39;simkai.ttf&#39;; 
imagefilledrectangle($im, 0, 0, 399, 29, $white); 
for($i=0;$i<$textlen;$i++) 
{ 
if($i==$p1||$i==$p2) 
{ 
imagettftext($im, 15, 0, 20*($i-1)+20, 20, $color_arr[$color], $font, iconv_substr($text,$i,1,&#39;utf-8&#39;)); 
} 
else 
{ 
imagettftext($im, 15, 0, 20*($i-1)+20, 20, $black, $font, iconv_substr($text,$i,1,&#39;utf-8&#39;)); 
} 
} 
imagepng($im); 
imagedestroy($im); 
?>

The characters in the verification code are not the same color, allowing users to enter the verification code of the specified color. This way security will be better.

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