a char higher

hi,

lets say user input a string such as "this is a string" and the program should give back the value one higher than the given string...

example : this is a string

answer: uhis is a string

i am doing it like this;

++str[0];

is there any other way, the reason being is that when i change like that, i dont give the original str anymore ..i dont want to use buffer where i need strcpy, etc....