Thread: Alphabet not changing

This compiles ok, but im getting wrong results. Im am trying to print the alphabet twice, once in uppercase, then call a function that changes the character size to lowercase and prints it back.

My output is showing them both as uppercase letters. I cant see anything wrong with my convert function. Is it just some silly mistake I have made?

Heres what I have done:

Code:

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

/*function prototype*/
void convert ( char* );

/*main function - begins program execution -----------------------------------*/
int main ( void )
{
   char let;

   for ( let = 'A'; let <= 'Z'; let++ )
   {
      printf("%2c", let);
   }

   convert ( &let );

   printf("\n\n");

   for ( let = 'A'; let <= 'Z'; let++ )
   {
      printf("%2c", let);
   }

   getchar(); /*freeze console output window*/

   return 0; /*return value from int main*/
}

void convert ( char *sPtr )
{
   while ( *sPtr != '\0' )
   {
      if ( toupper ( *sPtr ))
      {
         *sPtr = islower ( *sPtr );
      }

      sPtr++;
   }
}

On your second for loop have this instead:

Code:

for (let = 'a'; let <= 'z'; let++)
{
... // stuff
}

Code:

char let;
...
convert ( &let );

'let' isn't a string, its a single character, so your really only converting the last character ('Z').

islower() returns TRUE (!0) on if it's lower-case and FALSE (0) if its not.
http://www.mkssoftware.com/docs/man3/islower.3.asp
Therefore, the convert(&let) turns 'Z' into !0 ...

You're not actually converting case...

Thank you! I knew it was somthing stupid like that. I think I overlooked the second loop case. Cheers again

EDIT

Zacs7 I will amend my code. Good point and well spotted. I need new glasses

Why not store it in an array?

Code:

char Alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
int i;

printf("Uppercase: %s\n", Alphabet);
printf("Lowercase: ");
for(i = 0; i < sizeof(Alphabet)-1; i++)
{
    putchar(tolower(Alphabet[i]));
}
printf("\n");

or something...

Code:

>      if ( toupper ( *sPtr ))
>      {
>         *sPtr = islower ( *sPtr );
>      }

Should be:

Code:

      if ( isupper ( *sPtr ))
      {
         *sPtr = tolower ( *sPtr );
      }