関連ワード:  how to lowercase a character in c++    how to lowercase a char in c++    char to lowercase c++    how to uppercase a character in c++    how to lowercase a letter in c++    how to uppercase a letter in c++    how to make a character lowercase in c++    how to make a char lowercase in c++    how to convert a char to lowercase in c++    how to convert a lowercase char to uppercase in c++