Thread: Sorting Array Descending - need help!

This this my coding, i want to convert it into Descending and output like :

How many marks do you have [1 to 20] ? : 4
Enter mark 1 : 50
Enter mark 2 : 55
Enter mark 3 : 45
Enter mark 4 : 60

The sorted array in ascending order:
45
50
55
60

The sorted array in descending order:
60
55
50
45


The incomplete coding are below, can sumone help me finish it..

Code:

#include <stdio.h>
#include <conio.h>
#define k 20
int main()
{
  int a[k], n, p, j, i, small_j, smallest, biggest, big_j;
  printf("\nHow many marks do you have [1 to 20] ? : ");
  if(scanf("%d", &n) == 1 && n>0 && n<=k)
 {

	for(j=1; j<n+1; j++) {
	printf("Enter mark %d :  ",j);
	scanf("%d", &a[j]);
	}

	for(p=0; p<n; p++)
	{
		smallest = a[p];
		small_j = p;

		for(j=p; j<n+1; j++)
			if(a[j] < smallest)
			{
				smallest = a[j];
				small_j = j;
			}

			a[small_j] = a[p];
			a[p] = smallest;

	}

	printf("\nThe sorted array in ascending order:\n");
	for(j=0; j<n; j++) printf("%d\n", a[j]);
	}
return 0;
}

> for(j=1; j<n+1; j++)
Your sort and print function correctly start at index 0 in the array.

j = 0 ; j < n
is the best thing for looping over your array.

You can also use C++'s sort() - a comparison between qsort() and sort() at

http://theory.stanford.edu/~amitp/rants/c++-vs-c/

Salem: One can optimize the loop some more by using "j != n" instead of "j < n", which works as long as j and n are integers. I've also tried starting at n and decrementing to 0, as in

Code:

int j=n;
while (j--) {
  ...
}

which reduces the test to comparison with 0, although the difference, if any, is probably microscopic.

Edit: Sorry Salem, after reading your post more closely I saw you were concerned with the issue of getting the index right, not the efficiency (which shouldn't be an issue here).
Edit: Changed "j" to "j and n".