C++ regex

Question

I'm trying to use regular expressions in c++.
Example code:
/////////////////////////////////////////////////////////
#include <regex>
int main(){
std::regex pattern("([a-z]+)\\.txt");
return 0;
}
/////////////////////////////////////////////////////////
The code will compile. But when I run it I get regex_error exception.
I'm using this to compile it:
> g++ -std=c++11 example.cpp
my compiler version is 4.8.4.
Can someone help me?

Answer 1

ECMAScript is the default syntax for the standard library's regular expressions, which doesn't support brackets.
For your regex to work, use the Basic POSIX flag:
std::regex pattern("([a-z]+)\\.txt", std::regex_constants::basic);