Php regular expression replacement examples

Related concepts of PHP regular expression replacement:

Preg_replace: Search and replace regular expressions.

Mixed preg_replace (mixed pattern, mixed replacement, mixed subject [, int limit]) preg_replace: Allows you to replace the regular expression that matches your definition in the string.

A simple annotation removal function:

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Preg_replace ('[(/*) +. + (*/)]', '', $ val );

This code can remove multiple comments using/* comments */format in PHP and CSS. The three parameters are the regular expression, the string to be replaced, and the target string to be replaced (here the removal function is required, so it is a blank string-> ''). If you want to match sub-rules, you can use $0 to represent all matches, $1, $2, and so on.

Search for matches in pattern in subject and replace them with replacement. If limit is specified, only limit matches are replaced. If limit is omitted or its value is-1, all matches are replaced.

Replacement can contain reverse references in the form of // n or (starting from PHP 4.0.4) $ n. The latter is preferred. Each such reference will be replaced with the text that matches the child pattern in the nth captured parentheses. N can range from 0 to 99. // 0 or $0 indicates the text that is matched by the entire mode. Count left parentheses from left to right (starting from 1) to obtain the number of child modes.

When the replacement mode is followed by a reverse reference followed by a number (that is, the number next to a matching mode), the familiar // 1 symbol cannot be used to represent the reverse reference. For example,/11 will make preg_replace () confused about whether a reverse reference of // 1 is followed by a number 1 or a reverse reference of // 11. The solution in this example is to use/$ {1} 1. This will form an isolated $1 reverse reference, and make the other 1 just plain text.

Example 1:

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$ Jobname = "Executive Office-RH021001 front-end Secretary (job No.: RH021001 )"; $ Jobname = preg_replace ("/(. *)/", "", $ jobname ); $ Jobname = preg_replace ("/. *-. * 01/", "", $ jobname ); // Output: front-end Secretary

Example 2:

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$ Str = "<a href =" space. php? Uid = 109 "> fsb </a>"; s <a href = "space. php? Uid = 109 & do = thread & id = 174 "> Adjust your mindset to prevent mental fatigue in the workplace </a> ";   $ Str = preg_replace ("/space. php? Uid = (d +) & do = thread & id = (d +)/","/space-0-do-thread-id-0000000022.16.html ", $ str ); $ Str = preg_replace ("/space. php? Uid = (d +)/","/space-0000000012.16.html ", $ str );   // Output: <a href = "space. php? Uid = 109 "> fsb </a>"; s <a href = "/space-0-do-thread-id-174.html"> pay attention to adjust mentality to prevent mental fatigue in the workplace </a>

Example 3: Regular expression extraction or replacement of img tag attributes

 

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<? Php /* PHP regular expression extraction any attribute in the image img Mark */ $ Str = '<center> <br/> PHP regular expression extraction or image change img any attribute in the tag </center> '; // 1. Retrieve the entire image code Preg_match ('/<s * imgs + [^>] *? Srcs * = s * ('| ")(.*?) \ 1 [^>] *? /? S *>/I ', $ str, $ match ); Echo $ match [0]; // 2. Obtain the width Preg_match ('//I ', $ str, $ match ); Echo $ match [1]; // 3. Get the height Preg_match ('//I ', $ str, $ match ); Echo $ match [1]; // 4. Obtain src Preg_match ('//I ', $ str, $ match ); Echo $ match [1]; /* PHP regular expression to replace any attribute in the img Mark */ // 1. Replace src = "/uploads/images/20100516000.jpg" with src ="/uploads/uc/images/20100516000.jpg ") Print preg_replace ('/()/I ', "$ {1} uc/images/$ {3}", $ str ); Echo " // 2. Replace src = "/uploads/images/20100516000.jpg" with src ="/uploads/uc/images/20100516000.jpg" and save the width and height Print preg_replace ('/(/I ', "$ {1 }$ {2} uc/images/$ {3}>", $ str ); ?>