Analysis of filter_var() function and Filter function in PHP

This article mainly introduces the analysis of the filter_var() function and Filter function in PHP. It has a certain reference value. Now I share it with you. Friends in need can refer to it

PHP filter is used Validate and filter data from non-secure sources (such as user input)

filter_var() function filters a variable through a specified filter.
If successful, return filtered data, if failed, return false.
Syntax
filter_var(variable, filter, options)variable: required. Specifies the variables to filter.
filter: optional. Specifies the ID of the filter to use. (See FiltersID list below)
options: Specifies an array containing flags/options. Check the possible flags and options for each filter.

<? 
@header(&#39;content-type:text/html;charset=utf-8;&#39;); 
$email_a=&#39;jcifox@gmail.com&#39;; 
$email_b=&#39;@jcifox@gmail.com&#39;; 
$email_c=&#39;jcifoxgmail.com&#39;; 
$ip_a=&#39;0.0.0.0&#39;; 
$ip_b=&#39;255.255.255.255&#39;; 
$ip_c=&#39;0.0.0.265&#39;; 
echo $email_a.&#39;　:　&#39;; 
echo (filter_var($email_a,FILTER_VALIDATE_EMAIL))?&#39;is valid&#39;:&#39;is not valid&#39;; 
echo &#39;<br /><br />&#39;; 
echo $email_b.&#39;　:　&#39;; 
echo (filter_var($email_b,FILTER_VALIDATE_EMAIL))?&#39;is valid&#39;:&#39;is not valid&#39;; 
echo &#39;<br /><br />&#39;; 
echo $email_c.&#39;　:　&#39;; 
echo (filter_var($email_c,FILTER_VALIDATE_EMAIL))?&#39;is valid&#39;:&#39;is not valid&#39;; 
echo &#39;<br /><br />&#39;; 
echo $ip_a.&#39;　:　&#39;; 
echo (filter_var($ip_a,FILTER_VALIDATE_IP))?&#39;is valid&#39;:&#39;is not valid&#39;; 
echo &#39;<br /><br />&#39;; 
echo $ip_b.&#39;　:　&#39;; 
echo (filter_var($ip_b,FILTER_VALIDATE_IP))?&#39;is valid&#39;:&#39;is not valid&#39;; 
echo &#39;<br /><br />&#39;; 
echo $ip_c.&#39;　:　&#39;; 
echo (filter_var($ip_c,FILTER_VALIDATE_IP))?&#39;is valid&#39;:&#39;is not valid&#39;; 
?>

FiltersID name: Description
FILTER_CALLBACK: Call user-defined function to filter data.
FILTER_SANITIZE_STRING: Remove tags, remove or encode special characters.
FILTER_SANITIZE_STRIPPED: Alias ​​for "string" filter.
FILTER_SANITIZE_ENCODED: URL-encode string, remove or encode special characters.
FILTER_SANITIZE_SPECIAL_CHARS: HTML escape characters '"a8093152e673feb7aba1828c43532094& and characters with ASCII value less than 32.
FILTER_SANITIZE_EMAIL: Remove all characters except letters, numbers and !#$%&'* -/=?^ _`{|}~@.[]
FILTER_SANITIZE_URL: Delete all characters except letters, numbers and $-_. !*'(),{}|\\^~[]`a8093152e673feb7aba1828c43532094#% ";/?:@&=
FILTER_SANITIZE_NUMBER_INT: Remove all characters except numbers, - and -
FILTER_SANITIZE_NUMBER_FLOAT: Remove all characters except numbers, - and.,eE.
FILTER_SANITIZE_MAGIC_QUOTES: Apply addslashes().
FILTER_UNSAFE_RAW: No filtering, removal or encoding of special characters.
FILTER_VALIDATE_INT: Validates values ​​as integers in the specified range.
FILTER_VALIDATE_BOOLEAN: If it is "1", "true", "on" and "yes", it returns true, if it is "0", "false", "off", "no" and "", it returns false. Otherwise NULL is returned.
FILTER_VALIDATE_FLOAT: Validate value as a floating point number.
FILTER_VALIDATE_REGEXP: Validate values ​​based on regexp, a Perl-compatible regular expression.
FILTER_VALIDATE_URL: Validate the value as a URL.
FILTER_VALIDATE_EMAIL: Validate value as e-mail.
FILTER_VALIDATE_IP: Validate the value as an IP address.

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