Regular expressions

MySQL

Change telephone numbers of format 123 4567 to 020 123 4567

SELECT qname, tel FROM `restaurants` WHERE tel REGEXP  '^[0-9]{3}\ [0-9]{4}$'

UPDATE `restaurants` SET `tel` = CONCAT("020", tel) WHERE tel REGEXP  '^[0-9]{3}\ [0-9]{4}$'

Javascript

//$content = preg_replace('/(\[caption.*\])/', '', $content);

// () Grouping

// [ ] Character class

// ^ in [ ] is a NOT

// . Match any character (except newline)

// * Match preceding character 0 or more times

// + Match preceding character 1 or more times

// ? Match 1 or 0 times

// | OR(?)

// $ match end of input

// /i 

(.+?) = match any charchter more than once

// \s Match any white space character

// preg_replace('/(.+?)+(<\/tag>)/i', '', $string);

//$imgs = preg_match('/]+\>/i', $content);

//$howMany = preg_match_all('/]+>/i', $content, $matches, PREG_PATTERN_ORDER);

//$howMany = preg_match_all('/alt=\"([^\"]+)\".*src=\"([^\"]+)\".*width=\"([^\"]+)\".*height=\"([^\"]+)\"/i', $content, $images, PREG_PATTERN_ORDER);