Thread: 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.

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.

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