This document introduces regular expressions (regex) in PHP. It discusses the basic syntax of regex including patterns, indicators, quantifiers and logical operators. It provides examples of using the ereg and preg functions in PHP to perform matches and replacements using both POSIX and Perl-compatible regex. Common regex rules are also explained including matching characters, character classes, beginning/end of string, alternation and quantifiers.

1. Introduction PHP and REGEX Jussi Pohjolainen TAMK University of Applied Sciences

10. Some PERL regex rules REGEX Explanation Example . Any single character /a.c/ matches "abc" or "afc" [ ] Single character that is contained within the brackets /[abc]/ matches "a", or "b" or "c" ^ Find from the beginning of the string /^a/ matches " a ku ankka" $ Find from the end of the string /a$/ matches "aku ankk a " | OR /cat|dog/ matches "dog" or "cat" ^ NOT (when used in middle of pattern) /a^aa/ matches "aba" {n,m} Matches min n, max m /a{1,3}/ matches "a", or "aa", or "aaa" * Matches 0-n /a*/ ? Matches 0-1 /(hello)?/ + Matches 1-n /a+/

13. More Perl REGEX Rules REGEX Explanation [a-zA-Z0-9_] ^ [a-zA-Z0-9_] New Line Whitespace / Empty Not whitespaces / Empty Number Not Number