Problem in printing inverse array of an input array

Question

#include <stdio.h>
#include <conio.h>

void main()
{
  int arr[5], new[5], i, j;

  printf("ENTER ANY FIVE NUMBERS:");
  scanf("%d%d%d%d%d", &arr[0], &arr[1], &arr[2], &arr[3], &arr[4]);

  for(i=0; i<5; i++)
  {
    for(j=5; j>=0 ;--j)
    {
      new[i] = arr[j];
      printf("%d", new[i]);
      printf(" ");
    }
  }
  getch();
}

The above code is of a simple problem, which asks to take inputs of numbers in an array and show the inverse array of the input. I tried to solve it myself and wrote the above code. But the compiler is showing the result multiple times, I mean, the result should have only 5 numbers but the output shows series of numbers.

You have one for-loop too many.

G. Sliepen
– G. Sliepen

2018-10-20 11:23:27 +00:00
Commented Oct 20, 2018 at 11:23 — G. Sliepen
– G. Sliepen, Commented Oct 20, 2018 at 11:23

4386427 · Accepted Answer · 2018-10-20 11:34:45Z

1

Here is one problem:

for(j=5;j>=0;--j){
    new[i]=arr[j];
               ^ out of bounds access to arr[5]

Change it to

for(j=4;j>=0;--j){  // 4 instead of 5
    new[i]=arr[j];

That said, if all you want is to print an array in reverse order, simply do:

    for(j=4;j>=0;--j){
        printf("%d", arr[j]);
        printf(" ");
    }
    printf("\n");

No need for two loops and no need for the extra array new

If you really want a "reversed copy" do:

    for(j=4;j>=0;--j){
        new[4-j] = arr[j];
        printf("%d", arr[j]);  // or printf("%d", new[4-j]);
        printf(" ");
    }
    printf("\n");

edited Oct 20, 2018 at 11:34

answered Oct 20, 2018 at 11:27

4386427

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2 Comments

Nehal Samee Over a year ago

@user4386427 Thanks ...But I cant understand why does the two-loops not work ?

4386427 Over a year ago

@NehalSamee With two loops you get 5*6 calls of printf as your inner loop executes 6 times and your outer loop executes 5 times

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