Does this count as an Insertion-Sort? And why does a random number show at the end?

Question

I've been asked to create an insertion sort for an array. My program ended differently from the teacher's, but it sorts the array. However, I'm curious if it truly counts as a proper insertion sort. Also, at the end of the sorting, some random numbers appear. I would appreciate some help with this.

#include <iostream>
#define size  6
using namespace std;
void insertion(int v[size]){
    int i,temp;
    for(i=0;i<size;i++){
       while(v[i+1] < v[i]){
            temp = v[i+1];
            v[i+1] = v[i];
            v[i] = temp;
            printArr(v);
            i = 0;
            }
      }
}
int main(){
    int vet[size] = {34,12,15,21,5,88};
    printArr(vet);
    insertion(vet);
    
    return 0;

}

Here is the output, one line at a time:

34,12,15,21,5,88,
12,34,15,21,5,88,
12,15,34,21,5,88,
12,15,21,34,5,88,
12,15,21,5,34,88,
12,15,5,21,34,88,
12,5,15,21,34,88,
5,12,15,21,34,88,
5,12,15,21,34,44,

Notice the 44 at the end there. I don't know why it's there since the code works nicely up until the end.

Edit: Fixed a damn typo. My PC turns any lowercase i into uppercase, just forgot to adjust it, but it's not wrong in code.

This while loop while(v[i+1] < v[i]){ can access memory beyond the array when i is equal to size-1. — Vlad from Moscow, Jul 01 '22 at 19:43
v and vet are short for vetor, which means array in my language. So v[I] is an element in the i position of the array. — alexdovalle, Jul 01 '22 at 19:51

score 0 · Accepted Answer · answered Jul 01 '22 at 19:59

For starters there is a typo in this statement

v[i+1] = v[I];
         ^^^^

It seems you mean

v[i+1] = v[i];
         ^^^^

The while loop

   while(v[i+1] < v[i]){
        temp = v[i+1];
        v[i+1] = v[I];
        v[i] = temp;
        printArr(v);
        i = 0;
        }

can invoke undefined behavior due to accessing memory beyond the array when i is equal to size - 1.

In any case the approach with the while loop is incorrect and inefficient. The outer for loop again starts from 0 when a swap of adjacent elements occurred.

And moreover the function depends on the magic named number 6. That is it is unable to sort arrays of different sizes.

The uppercase i was just my pc being silly. It's correct in the actual code. Fixed the loop by making sure that i+1 < size. That's just a temporary fix, I'll improve the rest now. Thank you soo much hor your help. — alexdovalle, Jul 01 '22 at 20:13

score 0 · Answer 2 · answered Jul 01 '22 at 20:01

0

There is a variable mismatch. Change the capital I to small i.

answered Jul 01 '22 at 20:01

Manan Jain

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Does this count as an Insertion-Sort? And why does a random number show at the end?

2 Answers2