Verification code for PHP development

Many websites will have a verification code when logging in. Below we will introduce how to implement the verification code function.

There is this section in the code of the previous login page:

This is the picture of the verification code we see on the page. By giving the verification code image a click event, you can click the image once and change different numbers.

In addition, how the verification code is generated is the following code:

This is the background program for code generation.

Judge the code in the login back-end code. One is to judge whether there is input, and the other is to judge whether the input is correct. The code is as follows:

if(!$_POST['code']){ echo('验证码不能为空'); return; }else if($_POST['code']!=$_SESSION['VCODE']){ echo('验证码不正确'); return; }