Regular Expression Help

A Regular Expression is a search string and optionally a replacement string (see our Regular Expression Calculator):

Search String Rules

• ^ - matches start of line
• $ - matches end of line
• . - matches any single character
• [abc] - matches single a or b or c
• [^abc] - matches a character other than a or b or c
• (ab|cd) - matches ab or cd
• * - matches zero or any number of the previous character/expression
• + - matches one or more of the previous character/expression
• ? - matches zero or one of the previous character/expression
• {3} - matches three of the previous character/expression
• {3,} - matches at least three of the previous character/expression
• {3,5} - matches between three and five of the previous character/expression
• \n - matches New Line character
• \t - matches Tab character
• \f - matches Form Feed character
• \r - matches Carriage Return character
• \v - matches Vertical Tab character
• \d - matches any digit
• \D - matches a character other than a digit
• \w - matches any letter, digit or underscore (_)
• \W - matches a character other than a letter, digit or underscore (_)
• \s - matches any white space
• \S - matches a character other than a white space
• \b - matches a word boundary
• \B - matches a character other than a word boundary
• \. - matches an actual dot (works for all meta characters - including \)
• Other characters match with themselves

Replacement String Rules

• $& - replace with entire matched string
• $1 ... $9 - replace with first ... ninth matched bracketed () expression

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