string converting upper/lower

**jlamn** · 09-17-2002

I have a problem. I have to accept input and convert it to lower case if it is upper case, and vice versa. If i enter "HarrY" i should get "hARRy".
My code stops for some reason after a string has been entered. Can somebody please help me fix it up so that i can get it working. Here is what i have so far, as u can see i am a bit stumped with the reverseCase function:

Code:

#include <stdio.h>
#include <string.h>

#define STRINGSIZE 100

void getString(char *string);
void reverseCase(char *string);
int numGraph(char *string);


int main()
{
   char string[STRINGSIZE];
   int count;

   getString(string);
   printf("Entered string => %s", string);

   count = numGraph(string);
   printf("Number of graphic characters in string = %d\n", count);

   reverseCase(string);
   printf("Reverse case   => %s");

   return 0;
}

void reverseCase(char *string)
{
   /*converts uppercase into lowercase and lowercase into uppercase */
}

int numGraph(char *string)
{
   /* Calculate the number of printable graphic characters in the
      string.
   */

   int count;

   while (string != '\0')
   {
      if (isgraph((int) *string)) count++;
   }
   return count; 
}

void getString(char *string)
{
   printf("Please enter a string to process\n");
   fgets(string, STRINGSIZE, stdin);
}

**crag2804** · 09-17-2002

To convert case you have to add or subtract the difference between the ASCII values of the upper and lower case letters.

**Hammer** · 09-17-2002

Here's a correct version of numGraph()

Code:

#include <ctype.h>

int numGraph(char *mystring)
{
    /* Calculate the number of printable graphic characters in the mystring. */
    int    count = 0;

    while (*mystring != '\0')
    {
        if (isgraph((int) *mystring)) count++;
        mystring++;
    }

    return count;
}

Note that count is initialised to 0 (otherwise you don't know what its value is going to be. We dereference mystring on the while statement to get at the characters its pointing to, and we increment it at the end of the loop.

To write the reverseCase() function, try use the following:
islower()
isupper()
tolower()
toupper()

[edit]
>>To convert case you have to add or subtract the difference between the ASCII values of the upper and lower case letters.
This isn't guarenteed to work in all cases, so best stick with the standard functions.

**jlamn** · 09-17-2002

>>To convert case you have to add or subtract the difference between the ASCII values of the upper and lower case letters.
What exactly does this mean?

And when i use those islower function, isupper, how do i actually get to the individual string elements? Do i have to use some sort of a loop?

**jlamn** · 09-17-2002

>>To convert case you have to add or subtract the difference between the ASCII values of the upper and lower case letters.
What exactly does thie mean?

Also, how do i go about getting to each individual character in the string. Should i use a loop?

**jlamn** · 09-17-2002

>>To convert case you have to add or subtract the difference between the ASCII values of the upper and lower case letters.
What exactly does thie mean?

Also, how do i go about getting to each individual character in the string. Should i use a loop?

**jlamn** · 09-17-2002

>>To convert case you have to add or subtract the difference between the ASCII values of the upper and lower case letters.
What exactly does thie mean?

Also, how do i go about getting to each individual character in the string. Should i use a loop?

**quzah** · 09-24-2002

Originally posted by jlamn
>>To convert case you have to add or subtract the difference between the ASCII values of the upper and lower case letters.
What exactly does thie mean?

Also, how do i go about getting to each individual character in the string. Should i use a loop?

Just use 'toupper' or 'tolower', in the header ctype.h.

You can use a loop. Or you could use recursion:

Code:

void up( char*s )
{
    if( s && *s != '\0' )
    {
        *s=toupper(*s);
        up(s+1);
    }
}

Fun. Fun like the fun you had with the submit reply button...

Quzah.

**moi** · 09-24-2002

Originally posted by quzah
Just use 'toupper' or 'tolower', in the header ctype.h.

You can use a loop. Or you could use recursion:

Code:

void up( char*s ) { if( s && *s != '\0' ) { *s=toupper(*s); up(s+1); } }

Fun. Fun like the fun you had with the submit reply button...

Quzah.

dont you think recursion has a whole lot overhead for not doing much here?

Code:

deleted

edit: code example deleted because quzah has a good point

**quzah** · 09-24-2002

Originally posted by moi
dont you think recursion has a whole lot overhead for not doing much here?

You missed the entire point of the post. I don't do people's work for them. I tell them how ("You can use a loop.") and then provide an amusing alternative.

Quzah.

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