Thread: do-while loop doesn't work

for some reason my do-while implementation doesn't work. here is my code:

Code:

#include <stdio.h>

char getAns (char mesg[])
{
	char ans;
	printf ("&#37;s", mesg);
	ans = getchar();
	getchar();
	return toupper(ans);
}

void swap(int *p, int *q)
{
    int tmp;
	
    tmp = *p;
    *p = *q;
    *q = tmp;
}

void bubble (int a[], int N)
{
	int i, j;
	
	for (i = 0; i < N; i++)
		for (j = N - 1; i < j; j--)
		if (a[j - 1] > a[j])
			swap(&a[j - 1], &a[j]);
}

int	main (void)
{	
	char ans;
	int i, N;
	int a[N + 1];
	do
	{
	printf ("Enter the amount of numbers to be sorted: ");
	scanf ("%d", &N);
	printf("Now enter the numbers:\n");
	for (i = 0; i < N; i++){
		scanf ("%d", &a[i]);}
	bubble (a, N);
	for (i = 0; i < N; i++)
	printf("%d ", a[i]);
	printf("\nYour numbers were sorted using BubbleSort.\n");
	ans = getAns ("\nSort again (Y/N) ?");
	} while (ans == 'Y');
	return 0;
}

thanks for any suggestions

Originally Posted by Prelude

>int i, N;
>int a[N + 1];

That's wrong on multiple levels. First, N hasn't been initialized, yet it's an automatic variable. The value is indeterminate. Second, unless you're using C99, you can't use a non-constant value as the size for an array.

ok i added <ctype.h>...and yes i do realize that it was a stupid mistake, but the loop still doesn't work. Before i added the loop my program worked fine. Regarding the int i, N, i am not sure what C version i am using; since compiler gave no warnings and program functioned fine i assumed i made no big mistakes in the code.

ok cheers now it works. i swapped:
ans = getchar();
getchar();

for:
getchar();
ans = getchar():

and it works. thanks a lot

Your program is perfect in every way.

but ELYSIA how can you completely eliminate scanf from your program when getchar() is extremely cumbersome to use..
so it would be better to use fflush to flush out the buffer before using getchar() or any other related input function
isnt it??????

Originally Posted by ElemenT.usha

but ELYSIA how can you completely eliminate scanf from your program when getchar() is extremely cumbersome to use..

Originally Posted by Salem

Several FAQs deal with reading input. Concentrate on the ones which read input using fgets().

--------------------------------

Originally Posted by ElemenT.usha

so it would be better to use fflush to flush out the buffer before using getchar()

lulz.

Originally Posted by zx-1

--------------------------------


lulz.

so i dint get you my friend... what was lolz about??????

The implication of using fflush() on the stdin stream.