C ++ Regular Expression (regex)

Interest generated by the effect, even if the failure, but at least will not be extinct in the middle.

Regular Expressions. The syntax looks a lot better! This article provides a brief introduction: (Environment: Windows 7 + Visual Studio 2010)

# Include <regex> // header

1. Match the phone number

String tel_pattern ("13 ([5-8]) (\ d {8 })");

// Explanation: () indicates a subexpression, starting with a and 13. B, [5-8] indicates that the character is between '5' and '8'. c, \ escape, because d has a special meaning. d {8} represents eight numbers. Result: There are 11 numbers starting with 135-138.

String tel = "13512345678"; www.2cto.com

Bool match = regex_match (tel, tel_pattern );

2. Match the email address

String email_pattern ("(\ w +) (\. | _)? (\ W +) @ (\ w +) (\. (\ w +) + ");

// Explanation: w + indicates one or more words. | _ indicates. Or _,? 0 or 1, and + indicates repetition.

@ The meaning above is that there can be 1. Or _ between strings or no

@ Indicates that a word string starts with a. Word or multiple words.

3, separator string

[Cpp]
<Span style = "font-size: 14px;"> regex str_pattern ("(\\.)");
String str = "www.baidu.com ";
Sregex_token_iterator iter (str. begin (), str. end (), str_pattern,-1 );
Sregex_token_iterator end;
Vector <string> vec;
While (iter! = End)
{
Vec. push_back (* iter ++ );
Printf_s ("% s \ n", vec. back (). c_str ());
}
Printf_s ("% d \ n", vec. size (); </span>
Conclusion: Regular Expressions are powerful in usage and can be used to search, match, and separate expressions.

Important: the relationship between regular expressions and syntax tree and lexical analysis in compilation principles is too tight.