Fast one-liner to read a file into a string.

read.cc

#include <iostream>
#include <sstream>
#include <fstream>

int main() {
  std::string data = static_cast<std::ostringstream&>
    ( std::ostringstream() << std::ifstream("data.txt").rdbuf() ).str();
  std::cout << data << std::endl;
}