How to use <regex> in C++11

Question

I'm trying to use a regular expression to accept strings that have sequences like

ifelseifelseififif

So every else needs an if, but not every if needs an else. I know I could do this with pen and paper with a simple regular expression like this ((if)*+(ifelse)*)* .Now I'm not sure if I'll be able to do this with the library as I've never used it before. So would it be possible to accept or reject a string based on a regular expression like the one I wrote above?

I wrote this sample to get my feet wet and I don't understand why it returns false. Isn't regex_search() supposed to find substring matches? That snippet prints nope every time.

#include <regex>
#include <iostream>
using namespace std;

int main(){
  string sequence="ifelse";
  regex rx("if");
  if(regex_search(sequence.begin(),sequence.end(),rx)){
    cout<<"match found"<<endl;
  }else{
    cout<<"nope"<<endl;
  }
}

I'm using g++ 4.7 and have tried compiling with both g++ -std=gnu+11 reg.cpp and g++ -std=c++11 reg.cpp

Answer 1

This prints "match found", I just ran it. It wouldn't compile if you weren't using c++11 but heres how I compiled it. clang++ -std=c++11 -stdlib=libc++ reg.cpp

Answer 2

If you are compiling with g++ it may be because regex is not fully supported yet. See here for current C++11 status in g++.