How to generate verification code in PHP

Title: How to generate verification code in PHP

In web development, verification code (captcha) is often used to prevent machine automation operations to improve the performance of the website safety. This article will introduce how to use PHP to generate verification codes and provide specific code examples.

1. The principle and process of generating verification code
The principle of generating verification code is to embed a randomly generated picture in the page, and display the generated verification code text and picture to the user. You need to enter the verification code correctly when submitting the form.

The process of generating a verification code is as follows:

1. The server receives the request and starts generating the verification code;
2. The server generates a random verification code text;
3. The server generates the verification code text in the form of a picture;
4. The server returns the generated verification code picture to the front-end page;
5. The user enters the verification code in the front-end page;
6. When the user submits the form, compare the verification code text with the verification code entered by the user.

2. Code example for generating verification code through PHP
The following is a simple code example that shows how to use PHP to generate verification code:

3. Use Generate Verification code

In the front-end page, you can use the following HTML code to display the generated verification code image and input box:

When the back-end PHP code handles form submission, you can use the following Code to verify whether the verification code entered by the user is correct:

The above code implements the function of generating a verification code in PHP and verifying the verification code when the form is submitted. You can customize and optimize the style, length, character set, etc. of the verification code as needed.

Summary:
This article introduces how to generate verification codes in PHP and provides specific code examples. The process of generating a verification code includes steps such as generating random verification code text, drawing a verification code picture, and saving the verification code information. Through the use of verification codes, the security of web applications can be improved and machine automation operations can be prevented.

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