Sorting an array of integers using pointers

Question

I am trying to write a program that sorts an array (input by user) using pointers.
This is the code I wrote:

#include <stdio.h>
void main()
{
    int a[100],i,n,j,t;
    printf("Enter number of elements:\n");
    scanf("%d",&n);
    printf("Enter array:\n");
    for (i=0; i<n; i++)
    {
        scanf("%d",a+i);
    }
    for (i=0; i<(n-1); i++)
    {
        for (j=i+1; i<n; i++)
        {
            if (*(a+i)>*(a+j))
            {
                t=*(a+i);
                *(a+i)=*(a+j);
                *(a+j)=t;
            }
        }
    }
    printf("Sorted array (ascending) is:\n");
    for (i=0; i<n; i++)
    {
        printf("%d ",*(a+i));
    }
    printf("\n");
}

The compiler is not showing any errors.

Input:
5
1 5 4 2 8
Output:
1 8 4 2 5

I'm learning by myself and I got the idea that pointers are similar to arrays. I know how to do the same task with arrays but when I try here to substitute them with pointers it doesn't work.

What am I doing wrong here?

You are increasing i in both for loops; you should increase j instead of i; — Patrick Trentin
– Patrick Trentin, Commented Aug 28, 2017 at 20:57
Should I delete the question, since I see the mistake is pretty stupid (basically a typo)? I can't believe I missed it. — Plexus
– Plexus, Commented Aug 28, 2017 at 21:09
@Plexus I answered in the comments exactly for allowing you to do that since it was evidently a very minor error, but that's no longer possible (for you, at least) because there are positive-scored answers. Instead, you might want to revert your own edit fixing part of the question, since both answers quote the original source code and that might be confusing. — Patrick Trentin
– Patrick Trentin, Commented Aug 28, 2017 at 21:30
@PatrickTrentin yeah I figured that out, but everything was happening so fast, 2 answers came in like a couple of minutes after it, there were comments as well and I was also trying the program, so I didn't quite manage to do everything in time — Plexus
– Plexus, Commented Aug 28, 2017 at 21:38

Mohsen_Fatemi · Accepted Answer · 2017-08-28 21:00:28Z

2

the problem is in your second loop while you are sorting:

for (i=0; i<(n-1); i++)
    {
        for (j=i+1; i<n; i++)
        {
            if (*(a+i)>*(a+j))
            {
                t=*(a+i);
                *(a+i)=*(a+j);
                *(a+j)=t;
            }
        }
    }

you need to change the counter names to j :

for (i=0; i<(n-1); i++)
    {
        for (j=i+1; j<n; j++)
        {
            if (*(a+i)>*(a+j))
            {
                t=*(a+i);
                *(a+i)=*(a+j);
                *(a+j)=t;
            }
        }
    }

this line has the problem :

for (j=i+1; j<n; j++)

answered Aug 28, 2017 at 21:00

Mohsen_Fatemi

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3 Comments

Mohsen_Fatemi Over a year ago

it is always a possible danger for every programmer :D if you find my answer true, mark it as true answer

Plexus Over a year ago

Thanks, it is true, but now I'm so embarrassed for asking it

Mohsen_Fatemi Over a year ago

be proud of yourself, someone who scare of asking question have to be embarrased,not you , good luck ;)

Zamrony P. Juhara · Accepted Answer · 2017-08-28 22:03:47Z

2

I think it is because your j variable is not increased properly and wrong comparison is used (as suggested by Patrick). I think it should be as follow:

for(j=i+1; j<n; j++)

edited Aug 28, 2017 at 22:03

answered Aug 28, 2017 at 21:01

Zamrony P. Juhara

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