2.2 Regular Expression
2.2 Regular Expression
Some relative Basic Concepts Regular expressions represent patterns of strings of characters a regular expression r completely defined by the set of strings it matches The set is called the language of r written as L(r) · The set elements referred to as symbols This set of legal symbols called the alphabet and written as the greek symbol 2
Some Relative Basic Concepts • Regular expressions – represent patterns of strings of characters. • A regular expression r – completely defined by the set of strings it matches. – The set is called the language of r written as L(r) • The set elements – referred to as symbols • This set of legal symbols – called the alphabet and written as the Greek symbol ∑
Some relative Basic Concepts a regular expression r contains characters from the alphabet, indicating patterns, such a is the character a used as a pattern a regular expression r may contain special characters called meta-characters or meta-symbols An escape character can be used to turn off the special meaning of a meta-character Such as backslash and quotes
Some Relative Basic Concepts • A regular expression r – contains characters from the alphabet, indicating patterns, such a is the character a used as a pattern • A regular expression r – may contain special characters called meta-characters or meta-symbols • An escape character can be used to turn off the special meaning of a meta-character. – Such as backslash and quotes
More about regular expression 2. 2. 1 Definition of Regular Expression [ Oper 2.2.2 Extension to Regular Expression [ open] 2.2.3 Regular Expressions for Programming Language Tokens Open
More About Regular Expression 2.2.1 Definition of Regular Expression [Open] 2.2.2 Extension to Regular Expression [Open] 2.2.3 Regular Expressions for Programming Language Tokens [Open]
2. 2. 1 Definition of regular Expressions
2.2.1 Definition of Regular Expressions