PHP implements login verification code function and calling method

This article mainly introduces the login verification code function in PHP. The calling method is attached at the end of the article, and includes random character functions and GD library drawing functions. Interested friends can refer to

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:

The code is as follows:

<img  src="/static/imghwm/default1.png"  data-src="ShowKey.php"  class="lazy"   name="KeyImg" id="KeyImg"  onClick="KeyImg.src=&#39;ShowKey.php?&#39;+Math.random()" alt="PHP implements login verification code function and calling method" >

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