This is when you are sure the one_char is in lower case. Otherwise, do if statement.
But if you want to get down and dirty and assume ASCII and that the values are always
letters vs any possible character, and not use the ctype functions, then simply mask off
upper_charvalue = charvalue & ~(0x20);
It won't matter if the charvalue is upper or lower case. But it will trash characters
that are not letters.
If you use the toupper() function, it will only convert lower case characters to upper case
and leave other characters alone.