The verification code function will be used on the login interface.

Here we create a simple verification code file.

The production of a simple verification code is introduced in the "PHP Development User Login Module Production of Simple Verification Code" chapter of our PHP Chinese website "PHP Development Login Registration Tutorial", you can refer to it.

Create a verify.php file to facilitate subsequent calls

Set a 4-digit verification code here

<?php
session_start();
srand((double)microtime()*1000000);
while(($authnum=rand()%10000)<1000);//生成四位隨機(jī)整數(shù)驗(yàn)證碼
$_SESSION['auth']=$authnum;

//生成驗(yàn)證碼圖片
Header("Content-type: image/PNG");
$im = imagecreate(55,18);
$red = ImageColorAllocate($im, 255,0,0);
$white = ImageColorAllocate($im, 200,200,100);
$gray = ImageColorAllocate($im, 250,250,250);
$black = ImageColorAllocate($im, 120,120,50);

imagefill($im,60,20,$gray);

//將四位整數(shù)驗(yàn)證碼繪入圖片
//位置交錯(cuò)
for ($i = 0; $i < strlen($authnum); $i++)
{
   $i%2 == 0?$top = -1:$top = 3;
   imagestring($im, 6, 13*$i+4, 1, substr($authnum,$i,1), $white);
}

for($i=0;$i<100;$i++)   //加入干擾象素
{
   imagesetpixel($im, rand()%70 , rand()%30 , $black);
}

ImagePNG($im);
ImageDestroy($im);
?>