PHP implements website verification code function
This article mainly introduces the function of implementing website verification code in PHP. Interested friends can refer to it. I hope it will be helpful to everyone.
Verification code is a commonly used security measure on websites, and it is also a skill that is difficult for new webmasters to master. Here I will introduce to you a simple and effective verification code implementation method.
Before starting
Before we officially start, we need to turn on php's gd2 graphics library support (search for "php_gd2.dll" in php.ini, and find "; extension=php_gd2.dll" and remove the semicolon at the beginning of the sentence).
You can refer to: How to open the gd2 library of php
Core: img.php
This page generates a verification code and writes the correct value Enter Session
Randomly enter a 4-digit verification code
##$check=rand(1000,9999);
Write the generated verification code into the session
Session_start(); $_SESSION["check"] = $check;
Create A picture
$im = imagecreate(80,30);
imagefill($im,0,0,ImageColorAllocate($im, 255,255,255));
##Use imageline to randomly draw two solid lines
$y1=rand(0,30); $y2=rand(0,30); $y3=rand(0,30); $y4=rand(0,30); imageline($im,0,$y1,70, $y3,000); imageline($im,0,$y2,70, $y4,000);
Draw text in random positions
$strx=rand(3,15); $stry=rand(2,15); imagestring($img,5,$strx,$stry,substr($check,0,1),ImageColorAllocate($img,34,87,100)); $strx+=rand(15,20); $stry=rand(2,15); imagestring($img,5,$strx,$stry,substr($check,1,1),ImageColorAllocate($img,781,117,78)); $strx+=rand(15,20); $stry=rand(2,15); imagestring($img,5,$strx,$stry,substr($check,2,1),ImageColorAllocate($img,160,40,40)); $strx+=rand(15,20); $stry=rand(2,15); imagestring($img,5,$strx,$stry,substr($check,3,1),ImageColorAllocate($img,25,55,10));
Output image
Header("Content-type: image/PNG");
ImagePNG($img);End, the following is the complete code
Copy after login
I believe everyone knows how to do it, so I will give the code directly
<!DOCTYPE html> <html> <body> <form action="action.php" method="post"> <input type="text" name="cikle" placeholder="验证码"> <br> <img id="cikle" style="-webkit-user-select: none" src="img.php"><input type="submit" value="Submit"> </form> </body> </html>
The above code passes the value entered by the user to "action.php"
Check: action.phpThis step is to compare the user input value with the value in the session.
If they are equal, the output will be "correct"
If they are not equal, the output will be "incorrect"
<?php
Session_start();
if ($_SERVER["REQUEST_METHOD"] == "POST") {
if($_SESSION["check"]!=intval($_POST["cikle"])){
echo "不正确";
}else{
echo "正确";
}
}The above is the entire content of this article, I hope it will be helpful to everyone's study.
Related recommendations:
Function in PHP to verify whether the ID card is legal
Database content and display the value On page
The above is the detailed content of PHP implements website verification code function. For more information, please follow other related articles on the PHP Chinese website!
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