Regular Expression Syntax

Easy GREP RegEx can be written in the syntax of Javascript and VBscript which covers most of the usually used.

Essential Grammar & Syntax

Key Words

Metacharacters
Key Description Example Explanation
^ start of line ^On Key word "On" must be the first word of a line
$ end of line
. Anything except line feed One character, similar as ? in Windows wildcard
X* Preceding expression exists any times or not (.|\n)* Matches nothing or anything(even paragraphs) of any length
X+ Preceding expression exists once or more (.|\n)+ Anything(except nothing) of any length(>=1)
? Exists once or not ( Such as a,b,c or A,B,C
(XX) Make a group of characters, so that we can add other metacharacter behind or reference it in result (ab) Letter "a" and letter "b" share the same group
[XX] Make a class of characters, can match any characters inside. [ab] Letter "a" or letter "b"
(A|B) Similar as [AB], but A and B can be any length of characters, like word (a|abc) Letter "a" or word "abc"
| Either of two sides can match.
[^X] A class of all characters except the characters inside [^a] Anything except letter "a"
{a} Preceding expression should be repeated a times. {3} Exists three times
{a,b} Preceding expression should be repeated from a times to b times. {1,3} Exists one to three times
()? Preceding expression exists once or not. (a)? Letter "a "exists or not
? Match only to the nearest expression followed \.+?> Till the first ">"
Escaped Characters
Key Abbr. of Description Example Explanation
\d Digit means a number Such as 1,2,3
\b Boundary means a word boundary. (Some other types of RegEx use \< and \> do the same thing.) \bsome\b Only word "some" matches, "something" or "handsome" doesn't match
\r Return means carriage return For Mac system
\n Newline means newline For Windows system
\r\n whole line break Mostly for Windows system, also used in most files for cross-platform
\w Word Match any alphabetic character number and underscore. Match a whole word should be \b\w+\b Such as a,b,c or A,B,C generally equals to [a-zA-Z0-9_]
\s Space means white space, match space, tab and linebreak. Such as space or tab generally equals to [ \t\r\n]
\t Tab Tab character
\W ... An upper case means the negative class of the lowercase one means, reversed range.Such as \W match anything \w not match