18 if (
static_cast<unsigned>(ch -
'A') < 26u)
19 ch =
static_cast<char>(ch -
'A' +
'a');
23 std::string&
to_lower(std::string* str) {
24 std::transform(str->begin(), str->end(), str->begin(),
25 [](
char c) { return to_lower(c); });
29 std::string
to_lower(
const std::string& str) {
30 std::string str_copy(str.size(), 0);
31 std::transform(str.begin(), str.end(), str_copy.begin(),
32 [](
char c) { return to_lower(c); });