Detailed explanation of the function of generating image verification code in PHP

This article mainly introduces the function of PHP to generate image verification codes, and briefly introduces the operation skills of PHP to generate verification code images in the form of examples. It has certain reference value. Friends in need can refer to the following

for details As follows:

It simply uses a random function to generate images, without introducing the entire verification process.

The code is as follows:

<?php
/**
 * Created by JetBrains PhpStorm.
 * User: lee
 * To change this template use File | Settings | File Templates.
 */
header("content-type:image/png");
$validateLength=4;
$strToDraw="";
$chars=[
  "0","1","2","3","4",
  "5","6","7","8","9",
  "a","b","c","d","e","f","g",
  "h","i","j","k","l","m","n",
  "o","p","q","r","s","t",
  "u","v","w","x","y","z",
  "A","B","C","D","E","F","G",
  "H","I","J","K","L","M","N",
  "O","P","Q","R","S","T",
  "U","V","W","X","Y","Z"
];
$imgW=80;
$imgH=25;
$imgRes=imagecreate($imgW,$imgH);
$imgColor=imagecolorallocate($imgRes,255,255,100);
$color=imagecolorallocate($imgRes,0,0,0);
for($i=0;$i<$validateLength;$i++){
  $rand=rand(1,58);
  $strToDraw=$strToDraw." ".$chars[$rand];
}
imagestring($imgRes,5,0,5,$strToDraw,$color);
for($i=0;$i<100;$i++){
  imagesetpixel($imgRes,rand(0,$imgW),rand(0,$imgH),$color);
}
imagepng($imgRes);
imagedestroy($imgRes);

The running effect is as follows:

The above is this article The entire content, I hope it will be helpful to everyone's study.

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