Adapted from Not So Frequently Asked Questions:
#include <algorithm> #include <cctype> #include <string> std::string data = "Abc"; std::transform(data.begin(), data.end(), data.begin(), [](unsigned char c){ return std::tolower(c); });
You’re really not going to get away without iterating through each character. There’s no way to know whether the character is lowercase or uppercase otherwise.
If you really hate tolower()
, here’s a specialized ASCII-only alternative that I don’t recommend you use:
char asciitolower(char in) { if (in <= 'Z' && in >= 'A') return in - ('Z' - 'z'); return in; } std::transform(data.begin(), data.end(), data.begin(), asciitolower);
Be aware that tolower()
can only do a per-single-byte-character substitution, which is ill-fitting for many scripts, especially if using a multi-byte-encoding like UTF-8.