C + + Regular expression (regex) iterator (iterator) detailed

The regular expression (regex), using Boost's regex header file, is the new standard for c++11, but gcc4.8.1 is not fully supported, so use boost library;

Specific installation: http://blog.csdn.net/caroline_wendy/article/details/17282187

The writing specification of regular expressions, taking ECMAScript as an example, using iterators can traverse the original string and output all the strings conforming to the requirements;

Using the prefix () and suffix () methods, you can output the previous unmatched string and the latter unmatched string;

A subexpression of a regular expression (subexpressions) that can be segmented out of a regular expression and decomposed in a regular expression with parentheses "()";

The code is as follows:

#include <iostream> #include <string> #include <algorithm> #include <boost/regex.hpp>  
using namespace Std;  
      
using namespace boost;  
    int main () {std::string pattern ("[^c]ei");  
    Pattern = ' [: alpha:]]* ' + pattern + ' [: alpha:]]* '; Boost::regex R (pattern, regex::icase);  
    Ignores case std::string str ("Ruby carolinei biubiubiu weindy spikei winnceiy");  
            Use the regular iterator for traversal for (Boost::sregex_iterator it (str.begin), Str.end (), R), End_it; It!=end_it;  
      
    ++it) std::cout << it->str () << Std::endl;  
    Outputs the front and back strings of regular expressions std::cout << Std::endl;  
            For (Boost::sregex_iterator It (Str.begin (), Str.end (), R), End_it; It!=end_it;  
        ++it) {Auto pos = It->prefix (). Length (); pos = pos>40?  
        pos-40:0; Std::cout << It->prefix (). STR (). substr (POS)//Output the previous unmatched string */<< "\n\t\t>>>" &LT;&L T it-&GT;STR () << "<<<\n" << it->suffix (). STR (). substr (0, 40)/* The string after output * *  
    <<std::endl;  
    ///Match subexpression std::string filename ("File.cqp MyGod.cpP"); Boost::regex Rsub ([[: alnum:]]+) \. (  
    CPP|CXX|CC) $ ", regex::icase);  
    Smatch results;  
if (boost::regex_search (filename, results, rsub)) Std::cout << results.str (1) << Std::endl; }

Output:

Carolinei  
weindy  
spikei  
      
Ruby   
        >>>Carolinei<<<  
 biubiubiu weindy Spikei Winnceiy  
 biubiubiu   
        >>>Weindy<<<  
 spikei winnceiy  
       
        >>>SpikeI<< <  
 Winnceiy  
Mygod

Author: csdn Blog spike_king

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