file io question

**mike81** · 05-15-2007

Hi all,

In the following code i am trying to give the user the option to print to a chosen text file if they choose to. I have been reading up on pointers and file io and am still lost.

Any help offered would be greatly appreciated.

thanks in advance.
Mike

Code:

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

void mysort(char word[][100], int size);

int  i, a, x=0, j=0;

void main()
{
char word[10][100];
	printf("this program will sort up to 10 words in alphabetical order\n");
	printf("if you have fewer than 10 words enter <ctrl> z twice\n\n");
	for(a=0; a<10; a++)
		{
		printf("enter a word\n");
		
		if(scanf("%s", word[x]) != 1) break;
		x=x+1;
		j=x;
		}
		x=0;

	printf("original words\n--------------\n");
	for (i=0; i<j; i++)
		{
		printf("%s \n", word[i]);
		}

	mysort (word, j);
	printf("\nsorted words\n------------\n");
	for (i = 0; i <j; i++)
		{
		printf("%s \n", word[i]);
		}

}
void mysort(char word[][100], int size)
{
	int pass, indx;
	char hold[100];
	for(pass = 0; pass < size - 1 ; pass++)
		{
		for(indx = 0; indx < size - pass - 1; indx++)
			{
			if(strcmp(word[indx], word[indx + 1]) >0)
				{
				strcpy(hold, word[indx]);
				strcpy(word[indx], word[indx +1]);
				strcpy(word[indx + 1], hold);
				}
			}
		}	
}

**QuestionC** · 05-15-2007

Here is a small sample program that prompts the user for a file name and prints "Hello World" to that file. It shouldn't take much to add this functionality to what you've got.

Code:

#include <stdio.h>

int main (void) {
   char file_name[20];
   FILE * output;

   printf ("Enter a file name: ");

   scanf ("&#37;s", file_name);

   output = fopen (file_name, "w");

   fprintf (output, "Hello World!\n");

   return 0;
}

**MacGyver** · 05-15-2007

If you use scanf() in that manner, you can't accept a filename with spaces. If you wish to allow spaces, either use fgets() (and trim off the newline char) or change scanf() to accept more appropriate input.

**vart** · 05-15-2007

Several notes

1. void main should be int main
2. You don't need global vars - make them local in the main
3. You don't need both x and j - you can change the progem to use only one of them
4. Give your vars meaningfull names - not x, but wordCount for example
5. x=x+1 most peaple will write x++, it is more common notation for the same thing
6. You should work on your indentation - it will save you from some mistakes in the future

**mike81** · 05-16-2007

Thanks for you input guys,

Seems to be working. Now just need to figure out fgets().

Cheers,

Mike

**MacGyver** · 05-16-2007

Code:

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

int main(void)
{
	char buffer[BUFSIZ];
	size_t index;

	printf("Enter a string: ");
	fflush(stdout);
	fgets(buffer,sizeof(buffer),stdin);
	index = strlen(buffer) - 1;
	if(buffer[index] == '\n')
	{
		buffer[index] = '\0';
	}
	printf("You entered: <%s>\n",buffer);

	return 0;
}

**dwks** · 05-16-2007

Erhm . . . just don't type EOF (^Z for Windows) on a blank line. You'd be accessing buffer[(size_t)-1], which is almost certainly going to result in a segmentation fault.

You could fix that by checking the return value of fgets(): fgets() returns NULL if it encountered EOF or another error before it stored any characters in the array.

I like this version:

Code:

#include <stdio.h>  /* for fgets(), printf(), puts(), and BUFSIZ */
#include <string.h>  /* for strchr() */

int main() {
    char buffer[BUFSIZ], *p;

    if(fgets(buffer, sizeof buffer, stdin)) {
        if((p = strchr(buffer, '\n'))) *p = 0;
        printf("You entered [&#37;s]\n", buffer);
    }
    else puts("No string entered");

    return 0;
}

There are many different ways to strip the newline from a string created by fgets(). These are just two of them.

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