Regular expression syntax

Regular expression syntax is zero or more branches, separated by a "|" symbol. Regular expressions match anything that matches one of the branches, and a branch is zero or more concatenated pieces. The following examples describe the regular expression syntax:

Consider the following regular expression:

([a-zA-Z_][a-zA-Z0-9_]*)

This regular expression, enclosed in parentheses, matches a sequence of two ranges, any single uppercase or lowercase letter, or underscore character; followed by zero or more uppercase or lowercase letters, digits 0-9, or the underscore character.


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