PHP writing login verification code function with calling method

The example in this article shares a login verification code function written in PHP for your reference. The specific content is as follows

ShowKey.php

<?php
session_start();
//设置COOKIE或Session
function esetcookie($name,$str,$life=0){
//本函数将字符串 str 全部变小写字符串使验证码输入不区分大小写----在提交表单进行session比较同样需要次函数转化
 $_SESSION[$name]=strtolower($str);
}
 
//获取随机字符 此函数区分字符大小写 如果不区分大小写可加入函数strtolower
function domake_password($len) 
{ 
  $chars = array( 
    /*"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",*/ "0", "1", "2", 
    "3", "4", "5", "6", "7", "8", "9"
  ); 
  $charsLen = count($chars) - 1; 
  shuffle($chars);// 将数组打乱
  $output = ""; 
  for ($i=0; $i<$len; $i++) 
  { 
    $output .= $chars[mt_rand(0, $charsLen)]; //获得一个数组元素
  } 
  return $output;
} 
 
//显示验证码
function ShowKey(){
 $key=domake_password(4);//获取随机值
 $set=esetcookie("checkkey",$key);//将随机值写入cookie或session
 //是否支持gd库
 if(function_exists("imagejpeg")) 
 {
  header ("Content-type: image/jpeg");
  $img=imagecreate(47,20);
  $blue=imagecolorallocate($img,102,102,102);
  $white=ImageColorAllocate($img,255,255,255);
  $black=ImageColorAllocate($img,71,71,71);
  imagefill($img,0,0,$blue);
  imagestring($img,5,6,3,$key,$white);
  for($i=0;$i<90;$i++) //加入干扰象素
  {
   imagesetpixel($img,rand()%70,rand()%30,$black);
  }
  imagejpeg($img);
  imagedestroy($img);
 }
 elseif (function_exists("imagepng"))
 {
  header ("Content-type: image/png");
  $img=imagecreate(47,20);
  $blue=imagecolorallocate($img,102,102,102);
  $white=ImageColorAllocate($img,255,255,255);
  $black=ImageColorAllocate($img,71,71,71);
  imagefill($img,0,0,$blue);
  imagestring($img,5,6,3,$key,$white);
  for($i=0;$i<90;$i++) //加入干扰象素
  {
   imagesetpixel($img,rand()%70,rand()%30,$black);
  }
  imagepng($img);
  imagedestroy($img);
 }
 elseif (function_exists("imagegif")) 
 {
  header("Content-type: image/gif");
  $img=imagecreate(47,20);
  $blue=imagecolorallocate($img,102,102,102);
  $white=ImageColorAllocate($img,255,255,255);
  $black=ImageColorAllocate($img,71,71,71);
  imagefill($img,0,0,$blue);
  imagestring($img,5,6,3,$key,$white);
  for($i=0;$i<90;$i++) //加入干扰象素
  {
   imagesetpixel($img,rand()%70,rand()%30,$black);
  }
  imagegif($img);
  imagedestroy($img);
 }
 elseif (function_exists("imagewbmp")) 
 {
  header ("Content-type: image/vnd.wap.wbmp");
  $img=imagecreate(47,20);
  $blue=imagecolorallocate($img,102,102,102);
  $white=ImageColorAllocate($img,255,255,255);
  $black=ImageColorAllocate($img,71,71,71);
  imagefill($img,0,0,$blue);
  imagestring($img,5,6,3,$key,$white);
  for($i=0;$i<90;$i++) //加入干扰象素
  {
   imagesetpixel($img,rand()%70,rand()%30,$black);
  }
  imagewbmp($img);
  imagedestroy($img);
 }
 else
 {
  //不支持验证码
  header("content-type:image/jpeg\r\n");
  header("Pragma:no-cache\r\n");
  header("Cache-Control:no-cache\r\n");
  header("Expires:0\r\n");
  $fp = fopen("data/vdcode.jpg","r"); 
 }
}
ShowKey();
?>

Calling method:

<img src="ShowKey.php" name="KeyImg" id="KeyImg"  onClick="KeyImg.src=&#39;ShowKey.php?&#39;+Math.random()">

The above is the entire content of this article. I hope it will be helpful to everyone in learning PHP programming.

For more PHP functions of writing login verification codes, please pay attention to the PHP Chinese website for related articles with calling methods!