cppregex.cpp

#include <regex>
#include <iostream>
using namespace std;
int main()
{
	regex re("lo", regex_constants::icase);
	string target("Hello hello world");
		
    // Match first occurance of pattern
    /*

    // smatch. cmatch, wsmatch, wcmatch can be used
    // these template instance are used to store the actual match result
    smatch m;
	regex_search(target, m, re);
	cout << m.str() << '\n';
    */
    
    /*
    // Find all the matches
    // We must iterator to iterate through all the matches
    // Like smatch, sregex_iterator, cregex_iterator and so on can be used depending on the type of target
    for(auto match_itr = sregex_iterator(target.begin(), target.end(), re); match_itr != sregex_iterator(); ++match_itr)
    {
        smatch match = *match_itr;
        cout << match.str() << '\n';
        // smatch supports str, position, length member methods as well
    }
    */
    
    /*
    // Replace all the matched strings
    string new_str = regex_replace(target, re, "LO");
    cout << new_str << '\n';
    */
    
    // Find total how many matches are found
    auto mbegin = sregex_iterator(target.begin(), target.end(), re);
    auto mend = sregex_iterator();
    auto total_matches = distance(mbegin, mend);
    cout << total_matches << '\n';
    
    return 0;
}