The filter function in php verifies the mailbox, url, and IP address instance.

When I used php in my early years, I still didn't know the filter feature. At that time, I used regular expressions to determine whether the mailbox, url, and IP address format were consistent. Later, with the gradual development of the application, we realized that the built-in function library filter can also be used in php to complete these functions.

1. Verify email

First, let's look at the original regular expression verification.

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<? Php Function isEmail ($ email ){ If (preg_match ("/^ [0-9a-zA-Z] + @ ([0-9a-zA-Z] +) [.]) + [a-z] {2, 4} $/I ", $ email )){ Return 'mailbox verification OK '; } Else { Return 'verification is not a mailbox ';  } } ?>

Let's look at the filter.

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$ Email = 'sjlinyu @ qq.com '; $ Result = filter_var ($ email, FILTER_VALIDATE_EMAIL ); Var_dump ($ result); // string (14) "sjlinyu@qq.com"

For the filter_var function, if the verification succeeds, the verification object is returned; otherwise, false is returned.

I think the latter is simpler.

2. Verify the url address

Regular expression verification

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<? Php $ Url = 'www .111cn.net '; $ Search = '/--- regular N ---/'; If (preg_match ($ search, $ url )){ Echo 'matched '; } Else { Echo 'mismatched '; } ?>

Filter_var function

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$ Url = "http://www.111cn.net "; $ Result = filter_var ($ url, FILTER_VALIDATE_URL ); Var_dump ($ result); // string (22) "http://www.111cn.net"

3. Verify the IP address

Regular expression verification function

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/** * Check whether the IP address is correct. */ Function checkipaddres ($ ipaddres ){ $ Preg = "/A ([0-9]? [0-9]) | (1 [0-9] {2}) | (2 [0-4] [0-9]) | (25 [0-5]).) {3} ([0-9]? [0-9]) | (1 [0-9] {2}) | (2 [0-4] [0-9]) | (25 [0-5]) Z /"; If (preg_match ($ preg, $ ipaddres) return true; Return false; }

Verify this function

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$ Url = "192.168.1.110 "; $ Result = filter_var ($ url, FILTER_VALIDATE_IP ); Var_dump ($ result); // string (13) "192.168.1.110"

This method can also be used to verify ipv6.

 

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$ Url = "2001: DB8: 2de: e13 "; $ Result = filter_var ($ url, FILTER_VALIDATE_IP ); Var_dump ($ result); // string (17) "2001: DB8: 2de: e13"

Verify whether the value is an integer within an integer range

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$ I = '010 '; $ Result = filter_var ( $ I, FILTER_VALIDATE_INT, // Set the value range for verification Array ( 'Options' => array ('min _ range' => 1, 'max _ range' => 100)      )  ); Var_dump ($ result); // bool (false)

Php variables are of a weak type. If a filter is not used, it is true to use a variable greater than or less than the symbol.

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$ I = '010 '; $ Result = $ I >= 1 & $ I <= 100; Var_dump ($ result); // bool (true)

5. Verify floating point number

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$ Float = 12.312; $ Result = filter_var ($ float, FILTER_VALIDATE_FLOAT ); Var_dump ($ result); // float (12.312)

When verifying the amount, you often need to verify whether the amount is a floating point number.

Summary

Although the filter in php is relatively unpopular, it is quite powerful. In addition to the above features, there are also some filtering input functions, you can refer to the php Manual.