Detailed explanation of functions that come with PHP to verify whether email, URL, and IP are legal

In the past, I used PHP to verify whether the email, URL, and IP were legal by writing regular rules myself. However, sometimes I was confused and might write a regular rule that was not completely correct, causing verification errors. Today I discovered that PHP itself automatically With functions to verify whether the email, URL, and IP are legal

The filter_var function is mainly used.

Syntax

filter_var(variable, filter, options)

Parameter description

variable Required. Specifies the variables to filter.

filter Optional. Specifies the ID of the filter to use.

options Specifies an array containing flags/options. Check the possible flags and options for each filter.

PHP Filters

HTML escape characters ‘”<>& and characters with ASCII values ​​less than 32.Delete all characters , except numbers and -Remove all characters except numbers, - and.,eE.Apply addslashes().

ID Name	Description
FILTER_CALLBACK	Call user-defined function to filter data.
FILTER_SANITIZE_STRING	Remove tags, remove or encode special characters.
FILTER_SANITIZE_STRIPPED	"string" Alias ​​for the filter.
FILTER_SANITIZE_ENCODED	URL-encode string, remove or encode special characters.
##FILTER_SANITIZE_SPECIAL_CHARS
FILTER_SANITIZE_EMAIL	Remove all characters except letters, numbers and !#$%&'* -/=?^_`{| }~@.[]
FILTER_SANITIZE_URL	Remove all characters except letters, numbers and $-_. !*'(), {}|\\^~[]`<>#%”;/?:@&=
#FILTER_SANITIZE_NUMBER_INT
FILTER_SANITIZE_NUMBER_FLOAT
FILTER_SANITIZE_MAGIC_QUOTES
FILTER_UNSAFE_RAW	Does not do any filtering, stripping 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", then return true, if it is " 0″, “false”, “off”, “no” and “”, then false is returned. Otherwise NULL is returned.
FILTER_VALIDATE_FLOAT	Validate the value as a floating point number.
FILTER_VALIDATE_REGEXP	Validates values ​​based on regexp, a Perl-compatible regular expression.
FILTER_VALIDATE_URL	Validate the value as a URL.
FILTER_VALIDATE_EMAIL	Validate the value as an e-mail.
FILTER_VALIDATE_IP	Validate the value as an IP address.

Example #1 A filter_var() example

<?php
var_dump(filter_var(&#39;bob@example.com&#39;, FILTER_VALIDATE_EMAIL));
var_dump(filter_var(&#39;http://example.com&#39;, FILTER_VALIDATE_URL, FILTER_FLAG_PATH_REQUIRED));
?>

The above routine will output:

string(15) "bob@example.com"
bool(false)

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