How to convert std::string to lower case?

Question

I want to convert a std::string to lowercase. I am aware of the function tolower(), however in the past I have had issues with this function and it

Answer 1

Boost provides a string algorithm for this:

#include 

std::string str = "HELLO, WORLD!";
boost::algorithm::to_lower(str); // modifies str

Or, for non-in-place:

#include 

const std::string str = "HELLO, WORLD!";
const std::string lower_str = boost::algorithm::to_lower_copy(str);