Must know Regular Expressions with php

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Saman
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Must know Regular Expressions with php

Post by Saman » Mon Jul 18, 2011 10:41 pm

Here I'm posting a set of very useful regular expressions in php. Regular expressions are a powerful tool for examining and modifying text. preg_match is a powerful function of PHP that performs a regular expression match.

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int preg_match (string $pattern, string $subject [, array &$matches [, int $flags = 0 [, int $offset = 0 ]]] )
  1. Find a String in a String
    Find a string in a string can be done very easily by preg_match. Let’s have a look at the following two examples.
    The “i” after the pattern delimiter indicates a case-insensitive search

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    /*
Case Sensitive Search
*/
if ( preg_match("/cool/", "I love to share Cool things that help others. @lifeobject1") ) {
	echo "A match was found.";
}
else {
	echo "A match was not found.";
}

echo "<br />";

/*
Case Insensitive Search
*/
if ( preg_match("/cool/i", "I love to share Cool things that help others. @lifeobject1") ) {
	echo "A match was found.";
}
else {
	echo "A match was not found.";
}
    Output

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    A match was not found.
A match was found.
  2. Find a Word in a String
    Find a word in a string is a hot and regular requirement in the php development. PHP beautifully provides this solution and we will achieve this task by the following two examples of preg_match.
    The “\b” in the pattern indicates a word boundary, so only the distinct

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    /*
Word "profession" is matched, and not a word partial like "professional" or "professionalism"
*/
if ( preg_match("/\bprofession\b/i", "I am Software Engineer by profession. @lifeobject1") ) {
	echo "A match was found.";
}
else {
	echo "A match was not found.";
}

echo "<br />";

/*
Word "profession" is matched, and not a word partial like "professional" or "professionalism"
*/
if ( preg_match("/\bprofession\b/i", "My professional ethic is sharing. @lifeobject1") ) {
	echo "A match was found.";
}
else {
	echo "A match was not found.";
}
    Output

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    A match was found.
A match was not found.
  3. Find Domain Name from URL
    PHP developers often require to find a domain name from URL. preg_match provides a very easy solution. Let’s have a look into following examples.
    If matches is provided, then it is filled with the results of search. $matches[0] will contain the text that matched the full pattern, $matches[1] will have the text that matched the first captured parenthesized subpattern, and so on.

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    /*
Get host name from URL
*/
preg_match( '@^(?:http://)?([^/]+)@i', "https://robot.lk/category/php/", $matches );
$host = $matches[1];

echo "Host name is: " . $host;
echo "<br />";

/*
Get last two segments of host name
*/
preg_match('/[^.]+\.[^.]+$/', $host, $matches);
echo "Domain name is: " . $matches[0];
    Output

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    Host name is: robot.lk
Domain name is: robot.lk
  4. Valid IP Address Check
    preg_match makes the validity of IP address very easy. Let’s have a look into the following method which returns the validity of IP address professionally.
    Do not use preg_match() if you only want to check if one string is contained in another string. Use strpos() or strstr() instead as they will be faster.

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    /*
Valid IP Method
*/
function get_valid_ip( $ip ) {
	return preg_match("/^([1-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])" .
			"(\.([0-9]|[1-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])){3}$/", $ip );
}

/*
Valid IP Example
*/
$ip = "192.168.0.5";
if ( get_valid_ip( $ip ) ) {
	echo $ip . " is valid.";
}

echo "<br />";

/*
Invalid IP Example
*/
$ip = "256.157.0.5";
if ( ! get_valid_ip( $ip ) ) {
	echo $ip . " is not valid.";
}
    Output

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    192.168.0.5 is valid.
256.157.0.5 is not valid.
  5. US Phone Number Format Example
    Getting a US phone number format is a tough task as user may input phone number in different formats. Let’s have a look at the power of preg_match. You will notice a usage of preg_replace for the sake of getting US phone number format.

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    /*
US Phone Number Format Regex
*/
$regex = '/^(?:1(?:[. -])?)?(?:\((?=\d{3}\)))?([2-9]\d{2})'
			.'(?:(?<=\(\d{3})\))? ?(?:(?<=\d{3})[.-])?([2-9]\d{2})'
			.'[. -]?(\d{4})(?: (?i:ext)\.? ?(\d{1,5}))?$/';

/*
Different Formats
*/
$formats = array(
			'520-628-4539', '520.628.4539', '5206284539' ,
			'520 628 4539', '(520)628-4539', '(520) 628-4539',
			'(520) 628 4539', '520-628.4539', '520 628-4539',
			'(520)6284539', '520.628-4539', '15206284539',
			'1 520 628 4539', '1.520.628.4539', '1-520-628-4539',
			'520-628-4539 ext.123', '520.628.4539 EXT 123 ', '5206284539 Ext. 5889',
			'520 628 4539 ext 8', '(520) 628-4539 ext. 456', '1(520)628-4539');

/*
Let's Format Them
*/
foreach( $formats as $phoneNumber ) {

	if( preg_match($regex, $phoneNumber) ) {
		echo "Phone Number Matched " . $phoneNumber . " - US Format: " . preg_replace($regex, '($1) $2-$3 ext. $4', $phoneNumber);
		echo "<br />";
	}
}
    Output

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    Phone Number Matched 520-628-4539 - US Format: (520) 628-4539 ext.
Phone Number Matched 520.628.4539 - US Format: (520) 628-4539 ext.
Phone Number Matched 5206284539 - US Format: (520) 628-4539 ext.
Phone Number Matched 520 628 4539 - US Format: (520) 628-4539 ext.
Phone Number Matched (520)628-4539 - US Format: (520) 628-4539 ext.
Phone Number Matched (520) 628-4539 - US Format: (520) 628-4539 ext.
Phone Number Matched (520) 628 4539 - US Format: (520) 628-4539 ext.
Phone Number Matched 520-628.4539 - US Format: (520) 628-4539 ext.
Phone Number Matched 520 628-4539 - US Format: (520) 628-4539 ext.
Phone Number Matched (520)6284539 - US Format: (520) 628-4539 ext.
Phone Number Matched 520.628-4539 - US Format: (520) 628-4539 ext.
Phone Number Matched 15206284539 - US Format: (520) 628-4539 ext.
Phone Number Matched 1 520 628 4539 - US Format: (520) 628-4539 ext.
Phone Number Matched 1.520.628.4539 - US Format: (520) 628-4539 ext.
Phone Number Matched 1-520-628-4539 - US Format: (520) 628-4539 ext.
Phone Number Matched 520-628-4539 ext.123 - US Format: (520) 628-4539 ext. 123
Phone Number Matched 5206284539 Ext. 5889 - US Format: (520) 628-4539 ext. 588
Phone Number Matched 520 628 4539 ext 8 - US Format: (520) 628-4539 ext. 8
Phone Number Matched (520) 628-4539 ext. 456 - US Format: (520) 628-4539 ext. 456
Phone Number Matched 1(520)628-4539 - US Format: (520) 628-4539 ext.
  6. Valid Email Address Regex
    Email address validation is a regular requirement of PHP developers. Let’s see at following example.
    Because making a truly correct email validation function is harder than one may think, consider using with pure PHP through the filter_var function.

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    /*
Valid Email Address Regex
*/

function get_valid_email( $email ) {
	$regex = '/^([*+!.&#$¦\'\\%\/0-9a-z^_`{}=?~:-]+)@(([0-9a-z-]+\.)+[0-9a-z]{2,4})$/i';
	return preg_match($regex, trim($email), $matches);
}

/*
Different Emails
*/
$emails = array(
			'[email protected]',
			'[email protected]',
			'cool@yahoo',
			'kholi.net',
			'[email protected]',
			'[email protected]',
			'gem@yahoo.',);

			/*
Let's Check Them
*/
foreach( $emails as $email ) {

	if( get_valid_email( $email ) ) {
		echo "Valid Email: " . $email;
	}
	else {
		echo "Invalid Email: " . $email;
	}

	echo "<br />";
}

    Output

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    Valid Email: [email protected]
Valid Email: [email protected]
Invalid Email: cool@yahoo
Invalid Email: kholi.net
Valid Email: [email protected]
Valid Email: [email protected]
Invalid Email: gem@yahoo.
    Out of the Box: Email Address Validation with PHP filter_var function

    Let’s see at following example of email address validation with PHP through the filter_var function.

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    /*
Valid Email Address filter_var
*/
function get_valid_email( $email ) {
	return filter_var( $email, FILTER_VALIDATE_EMAIL );
}

/*
Different Emails
*/
$emails = array(
			'[email protected]',
			'[email protected]',
			'cool@yahoo',
			'kholi.net',
			'[email protected]',
			'[email protected]',
			'gem@yahoo.',);

/*
Let's Check Them
*/
foreach( $emails as $email ) {

	if( get_valid_email( $email ) ) {
		echo "Valid Email: " . $email;
	}
	else {
		echo "Invalid Email: " . $email;
	}

	echo "<br />";
}
    Output

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    Valid Email: [email protected]
Valid Email: [email protected]
Invalid Email: cool@yahoo
Invalid Email: kholi.net
Valid Email: [email protected]
Valid Email: [email protected]
Invalid Email: gem@yahoo.
  7. Validate URL Regular Expression
    We can use preg_match for the validation of any type of URL. Let’s have a look into the code snippet of PHP URL Validation.

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    /*
Validate URL Regular Expression
*/
function get_valid_url( $url ) {

	$regex = "((https?|ftp)\:\/\/)?"; // Scheme
	$regex .= "([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?"; // User and Pass
	$regex .= "([a-z0-9-.]*)\.([a-z]{2,3})"; // Host or IP
	$regex .= "(\:[0-9]{2,5})?"; // Port
	$regex .= "(\/([a-z0-9+\$_-]\.?)+)*\/?"; // Path
	$regex .= "(\?[a-z+&\$_.-][a-z0-9;:@&%=+\/\$_.-]*)?"; // GET Query
	$regex .= "(#[a-z_.-][a-z0-9+\$_.-]*)?"; // Anchor

	return preg_match("/^$regex$/", $url);
}

/*
Different URLs
*/
$urls = array(
			'https://robot.lk/',
			'https://robot.lk/viewtopic.php?f=41&t=2619',
			'http://www.google.com/#sclient=psy&hl=en&source=hp&q=robotlk&aq=f&aqi=&aql=&oq=&pbx=1&bav=on.2,or.r_gc.r_pw.&fp=97eede9ed711c932&biw=1920&bih=895',
			'ftp://some.domaon.com/',
			'wwwwelcomecom',
			'tcp://www.domain.com',
			'http://wordpress.org',
			'https:www.secure.net',
			'https://.com',
			'https://www.lock.com',
			'https://robot.lk');

/*
Let's Check Them
*/
foreach( $urls as $url ) {

	if( get_valid_url( $url ) ) {
		echo "Valid URL: " . $url;
	}
	else {
		echo "Invalid URL: " . $url;
	}

	echo "<br />";
}
    Output

    Code: Select all

    Valid URL: https://robot.lk/
Valid URL: https://robot.lk/viewtopic.php?f=41&t=2619
Valid URL: http://www.google.com/#sclient=psy&hl=en&source=hp&q=robotlk&aq=f&aqi=&aql=&oq=&pbx=1&bav=on.2,or.r_gc.r_pw.&fp=97eede9ed711c932&biw=1920&bih=895
Valid URL: ftp://some.domaon.com/
Invalid URL: wwwwelcomecom
Invalid URL: tcp://www.domain.org
Valid URL: http://wordpress.org
Invalid URL: https:www.secure.net
Valid URL: https://.com
Valid URL: https://www.lock.com
Valid URL: https://robot.lk
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