Thread: Invert characters will convert all non capital letters to '?'

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.

Code:

#include <ctype.h>
#include <stdio.h>

char invert(char c)
{
     if(isalpha(c)==0)/*not a letter*/
          return c;
     if('c'<=132)/*then it is uppercase.remember we know it is a letter*/
         c+=32;
     else
        c-=32;

     printf("edw %c\n",c);

     return c;
}

After-question : is alpha safe to use? Because this isalpha - C++ Reference made me a little bit worried(the section that says about locales)

Thank you in advance and sorry for the question

If you want this: "hello, WORLD" -> "HELLO, world", look at line 8.

You are using 'c' instead of the variable c. Double check your ascii values, I'd probably use ascii value dec (90) instead of oct (132)?

Excellent.Problem solved.However the question about the isaplha still remains.

Thank you fnprintf.Now i can go to bed with a smile

You could also use if(c < 'a') since you know that you have passed isalpha() at that point. There is also toupper() and tolower() functions in ctype.h

subsonics i did not want to use them,in order to play a little with the characters.

iMalc you are right about the ascii codes