gnu regular expression tutorial

Original address: Http://javascript.info/tutorial/regexp-introductionBrief introductionRegular expressions have a very powerful function for string "Find" and "replace". In JS, it is integrated in the string method: Search, match, and replace.A regular expression, consisting of a pattern(matching rule) and a flags(modifier-optional).A basic

Regular expressions are detailed. Regular expressions in PHP (1) PHP inherits the consistent tradition of * NIX and fully supports the processing of regular expressions. Regular expressions provide an advanced, but not intuitive string matching and processing of regular expr

VBS Tutorial: regular expression syntax Regular expression syntax A regular expression is a text mode consisting of common characters (such as characters a to z) and special characters

is used, "$" will match the end of the absolute string instead of the newline character, which is turned on by default. U Greedy mode, similar to the role of question marks, the maximum match is greedy mode. the common metacharacters Code Description . Match any character except newline (\r\n,\r,\n) \w Match letters or numbers or underscores or kanji \s Matches any

collection of atomsMatch any character except line break. Any character other than a line break\d matches any decimal number, i.e. [0-9]\d matches any non-decimal number, i.e. [^0-9]\s matches an invisible atom, i.e. [\f\n\r\t\v]\s matches a visible atom, i.e. [^\f\n\r\t\v]\w matches any number, letter, or underscore, i.e. [0-9a-za-z]W: matches any word character that includes an underscore. Similar but not equivalent to "[a-za-z0-9_]", where the "word" character uses the Unicode character set.

PHP Tutorial pcre Regular Expression Complete tutorialPredefined constants Preg_pattern_order The results are sorted by "rules", only for Preg_match_all, i.e. $matches[0] is the result of a complete rule, $matches [1] is the result of the first subgroup matchPreg_set_order: The results are sorted by "set" only for Preg_match_all, that is, $matches[0] saves all

Php regular expressions are used to obtain all the URLs and link texts of a webpage. Php Tutorial regular expression get all web pages and link text $ urlwww.111cn.net; $ body @ file_get_contents ($ url); preg_match_all (href []? ([^] *) []? (. *) I, $ body, $ B php Tutorial

Php regular expressions match gb2312 and UTF-8 Chinese characters .? Php Tutorial $ actiontrim ($ _ get [action]); if ($ actionsub) {$ str $ _ post [dir]; if (! Preg_match (^ [. chr (0xa1).-. chr (0xff). A-Za-z0-9 _] + $, $ str) gb2312 $ Action = trim ($ _ get ['action']);If ($ action = "sub "){$ Str = $ _ post ['dir'];// If (! Preg_match ("/^ [". chr (0xa1 ). "-". chr (0xff ). "A-Za-z0-9 _] + $/",

Special Charactersin regular style, some characters have special usage: [ \ ^ $ . | ? * + ( ).They are special because they are used to enhance the regular matching function. Don't try to memorize them, and when we've all used them, you can easily remember them.to use a special character as an ordinary identity, you must escape it . In other words, you need to precede the backslash.For example, we want to f

DFA engine they do not require backtracking (and therefore they never test the same characters two times), so the match is fast ! The DFA engine can also match the longest possible string. However, the DFA engine contains only a limited state, so it cannot match a pattern with a reverse reference, and no subexpression can be captured . Representative: awk,egrep,flex,lex,mysql,procmail NFA non-deterministic Finite automaton is a finite automaton, and is divided into tra

PHP Tutorial Regular expression validation numbers Non-negative floating-point number (positive floating point + 0): ^d+ (. d+)? $Positive floating-point number ^ ([0-9]+.[ 0-9]*[1-9][0-9]*) | ([0-9]*[1-9][0-9]*. [0-9]+) | ([0-9]*[1-9][0-9]*)) $Non-positive floating-point number (negative floating-point number + 0) ^ ((-d+ (. d+)?) | (0+ (. 0+)?)) $Negative floa

modifierA regular may contain a modifier that can affect search results.There are 3 modifiers in JS:g: Find all results;I: result ignoring case;m: Multi-line matching mode;Modifier is placed after the parameter, such as:/.../g.A regular with no global modifier returns only the first matching value:1 alert ("123". Match (/\d/)) // ' 1 'If there is a global modifier, all matching values will be returned:1 a

The format of the string intercepted by php regular expression is This is what it looks like How can I intercept the contents in src = "", that is, the red part. Thank you for your guidance. Reply to discussion (solution) $s=txt;preg_match('/src="(.+?)"/i', $s, $m);echo $m[1]; $ S = How can I intercept the contents in src = "...", that is, the red part. Tuto