Get variables from input data using PHP function 'filter_input'

Title: Use the PHP function "filter_input" to obtain variables from input data

Introduction:
In PHP, processing user input is a very important step to ensure the validity and security of the data. PHP provides many functions to filter and validate user input, one of the very useful functions is "filter_input". This article will introduce how to use this function to obtain variables from input data, and give relevant code examples.

1. Introduction to the "filter_input" function
   The "filter_input" function is a powerful function used to obtain variables from input data. It is able to filter, validate and convert different types of data input by users, such as: strings, integers, floating point numbers, URL addresses, emails, etc. This function can accept three parameters: input type, variable name and filter flag.
2. Commonly used input types
   The following are several commonly used input types (can be replaced by constants):
3. INPUT_GET: Get the variables submitted through the GET method
4. INPUT_POST: Get the variables submitted through the POST method
5. INPUT_COOKIE: Get the variables submitted through the Cookie
6. INPUT_SERVER: Get the variables submitted through the server environment
7. INPUT_ENV: Get the variables submitted through the environment variables Variables
8. Commonly used filters
   The following are several commonly used filters (can be replaced by constants):
9. FILTER_VALIDATE_INT: Verify the validity of integers
10. FILTER_SANITIZE_STRING: Remove Illegal characters in the string
11. FILTER_VALIDATE_EMAIL: Verify the validity of the email address
12. FILTER_VALIDATE_URL: Verify the validity of the URL address
13. FILTER_SANITIZE_NUMBER_FLOAT: Remove characters other than numbers in the string characters and convert the number to a floating point number
14. Usage example
    Here is a sample code that uses the "filter_input" function to get a variable from the input data:

<?php
// 从GET方法中获取名为 "username" 的字符串变量
$username = filter_input(INPUT_GET, 'username', FILTER_SANITIZE_STRING);

// 从POST方法中获取名为 "age" 的整数变量
$age = filter_input(INPUT_POST, 'age', FILTER_VALIDATE_INT);

// 从COOKIE中获取名为 "email" 的电子邮件地址变量
$email = filter_input(INPUT_COOKIE, 'email', FILTER_VALIDATE_EMAIL);

// 从SERVER环境中获取名为 "ip" 的IP地址变量
$ip = filter_input(INPUT_SERVER, 'REMOTE_ADDR', FILTER_VALIDATE_IP);
?>

In this In the example, we use the "filter_input" function to obtain different variables from different input types. By specifying appropriate filter flags, we can ensure the validity and security of the input data.

5. Conclusion
   Using the PHP function "filter_input" can easily obtain variables from the input data, and perform filtering and verification. This function is very useful when processing user input and can effectively protect the application from malicious input attacks.

This article introduces how to use the "filter_input" function and gives relevant code examples. I hope it will be helpful to readers in processing user input in PHP development.

Reference materials:

• PHP official documentation: https://www.php.net/manual/en/function.filter-input.php

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