How to use filter_var() function in PHP? (code example)

In PHP, the filter_var() function will use the specified filter to filter variables; it can filter the data passed by the user. The following article will introduce to you the usage of filter_var() function. I hope it will be helpful to you. [Video tutorial recommendation: PHP tutorial]

##PHP filter_var() function

The filter_var() function filters a variable using the specified filter; it can be used to validate and filter data.

Basic syntax

filter_var(var, filtername, options)

Parameters: filter_var() function accepts three parameters

●var: indicates what to filter Variable, cannot be omitted (required parameter).

● filtername: used to specify the ID or name of the filter to be used. The default value is FILTER_DEFAULT, which causes no filtering; can be omitted.

● Options: Used to specify one or more flags/options to be used. Checks each filter for possible options and flags; may be omitted.

Return value: If the filtering is successful, the filtered data will be returned; if the filtering fails, FALSE will be returned.

Usage example of PHP filter_var() function

Example 1: Filter string

<?php 
  
$str = "hello php er7y6t258u8@%^^%%$$#++!"; 
$newstr = filter_var($str, FILTER_SANITIZE_NUMBER_INT); 
echo $newstr; 
  
?>

Output:

762588++

Description: FILTER_SANITIZE_NUMBER_INT means to delete all other characters except numbers and -.

Example 2: Verify IP address

You can use the filter_var() function to verify whether the specified ip address is valid.

<?php 
header("content-type:text/html;charset=utf-8"); 
$ip = "127.0.0.1"; 
if (!filter_var($ip, FILTER_VALIDATE_IP) === false) { 
    echo("$ip 是有效的IP地址"); 
} else { 
    echo("$ip 不是有效的IP地址"); 
} 
  
?>

Output:

127.0.0.1 是有效的IP地址

Example 3: Filter and verify email (email) addresses

The filter_var() function first starts from Remove all illegal characters from the variable containing the email address and then check if it is a valid email address:

<?php 
header("content-type:text/html;charset=utf-8"); 
$email = "148521425@qq.com"; 
  
// 从电子邮件中删除所有非法字符
$email = filter_var($email, FILTER_SANITIZE_EMAIL); 
  
// 判断是否为有效的电子邮件 
if (!filter_var($email, FILTER_VALIDATE_EMAIL) === false) { 
    echo("$email 是一个有效的电子邮件地址"); 
} else { 
    echo("$email 不是一个有效的电子邮件地址"); 
} 
  
?>

Output:

148521425@qq.com 是一个有效的电子邮件地址

Example 4: Filter and verify URL

filter_var() function first removes all illegal characters from the URL and then checks if it is a valid URL:

<?php 
header("content-type:text/html;charset=utf-8"); 
$url = "https://www.php.cn"; 
  
// 从URL中删除所有非法字符
$url = filter_var($url, FILTER_SANITIZE_URL); 
  
// 验证URl是否有效
if (!filter_var($url, FILTER_VALIDATE_URL) === false) { 
    echo("$url 是一个有效的URL"); 
} else { 
    echo("$url 不是一个有效的URL"); 
} 
  
?>

Output:

https://www.php.cn 是一个有效的URL

The above is the entire content of this article, I hope it will be helpful to everyone's study. For more exciting content, you can pay attention to the relevant column tutorials on the PHP Chinese website! ! !

The above is the detailed content of How to use filter_var() function in PHP? (code example). For more information, please follow other related articles on the PHP Chinese website!