Help with string program

Hi, I need urgent help for this program, sorry I am new to C and I got this code:

Code:

---

#include <stdio.h>

#define STRINGSIZE 100

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


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

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

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

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

  return 0;
}

void reverseCase(char *string)
{
  /* Reverse the case of all alphabetic characters in the string.
      That is, all upper case characters become lower case and
      all lower case become upper case.
  */
        char c;

          while((c = getchar()) != EOF)
            putchar(isupper(c) ? tolower(c) : toupper(c));
}

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)
{
  char c;
  printf("Please enter a string to process\n");
  scanf("%s", c);
  fgets(string, STRINGSIZE, stdin);
}

---

What I am trying to achieve is for the program to first ask me to input a string, then I need the program to show me the string I entered, count the number of characters entered and then convert the string to upper case or vice versa depending on the string I entered.

This code is for some reason throwing me a runtime error, I am not sure what I am doing wrong. Any help will be appreciated. Thanks.

Code:

---

char c;
scanf("%s", c);

---

The you've said its a string, yet 'c' is infact a char (use %c) although this statement is pointless...

isalpha, tolower ect are declared in ctypes.h (your not including this).

Theres no need to cast the arg to int in isgraph((int) *string))...

Why not count the chars with strlen() from string.h???

hth..

OK, thanks, I have changed the code to this:

Code:

---

#include <stdio.h>
#include <ctype.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", string);

  return 0;
}

void reverseCase(char *string)
{
  /* Reverse the case of all alphabetic characters in the string.
      That is, all upper case characters become lower case and
      all lower case become upper case.
  */
        int c;

          while((c = getchar()) != EOF)
            putchar(isupper(c) ? tolower(c) : toupper(c));
}

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

  int count;

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

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

---

It is only showing me the entered string and not executing numGraph or reverseCase, not sure why not. :(

It would be a good idea to at read up on the of C (pointers, loops, ect)...

Your problem lies in numGraph... You have an infinite loop...

Code:

---

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

  int count;

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

---

Well 'string' is most probably never going to be NULL (you don't change its value anywhere) = infinite loop.
Redesign it...

Hi, I'd like to first of all thank people for the help, my little string converter program is nearly finished, I am only stuck on the function of converting the letters from the string from lower case to upper case and vice versa, this is what the code looks like now:

Code:

---

#include <stdio.h>
#include <ctype.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\n",string);

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

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

  return 0;
}

void reverseCase(char *string)
{
  /* Reverse the case of all alphabetic characters in the string.
      That is, all upper case characters become lower case and
      all lower case become upper case.
  */

          while((*string = getchar()) != EOF)
            putchar(isupper(string) ? tolower(string) : toupper(string));
}

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

        int i,count;

        for(i = 0,count = 0;string[i] != '\0';i++)
        {
                if (isgraph((int)string[i])) count++;
        }
        return count;
}

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

---

It compiles and runs fine until it gets to the reverseCase function that thrwos me a segmentation fault. Anyone know what I am doing wrong?

Thanks

Code:

---

void reverseCase(char *string)
{
  /* Reverse the case of all alphabetic characters in the string.
      That is, all upper case characters become lower case and
      all lower case become upper case.
  */

          while((*string = getchar()) != EOF)
            putchar(isupper(string) ? tolower(string) : toupper(string));
}

---

This code reads from the console instead of reading from the string. You need to change this into a loop just like in numGraph and then change the value inside the array string instead of writing to the console.

Hi pplz, I managed to get the program working correctly now using this code:

Code:

---

#include <stdio.h>
#include <ctype.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", string);

  return 0;
}

void reverseCase(char *string)
{
  /* Reverse the case of all alphabetic characters in the string.
      That is, all upper case characters become lower case and
      all lower case become upper case.
  */

        int i;

        for (i = 0; string[i] != '\0'; i++)
        {
                if (isgraph((int)string[i]))
                {
                        if (islower(string[i])) string[i] = toupper(string[i]);
                        else if (isupper(string[i])) string[i] = tolower(string[i]);
                }
        }
}

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

        int i, count = 0;

        for (i = 0; string[i] != '\0';i++)
        {
                if (isgraph((int)string[i])) count++;
        }
        return count;
}

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

---

Now, this program compiles correctly with no errors and executes correctly too and produces the desired output, so you might be asking what the problem is. Well, I have to submit this file via a system that uses a special compiler and this annoying compiler throws me the following error in these two lines:

if (islower(string[i])) string[i] = toupper(string[i]);
else if (isupper(string[i])) string[i] = tolower(string[i]);

Error: Warning: subscript has type 'char'

And therefore this compiler won't let me submit this file, I am not sure why it is giving me such error, it compiles and runs fine with my C compiler but this other compiler that I need it to compile fine too throws me these errors. Can anyone suggest why? And how can I fix this? Any help would be enormously appreciated.

islower and isupper takes as parameter a character, casted to an int. See what you did for isgraph and do the same for islower/isupper.

Never mind guys, I fixed it up now, I had to cast the string[i] to int on those two lines as well. Fixed and submitted now, thanks for your help :)