Sorry for asking this :/
Purpose : Invert every single letter to uppercase or downcase depending what is it's state.
Problem : Invert characters will convert all non capital letters to '?'
Notice : i am pretty sure that the function receives the characters as it supposed to.
After-question : is alpha safe to use? Because this isalpha - C++ Reference made me a little bit worried(the section that says about locales)
char invert(char c)
if(isalpha(c)==0)/*not a letter*/
if('c'<=132)/*then it is uppercase.remember we know it is a letter*/
Thank you in advance and sorry for the question