Bubble Sorting In C : garbage value error

Question

So recently I have been Learning data structures in C . Now let's come to my problem

Here is my Code of Bubble Sort Algo :

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

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

int main() {
  int arr[] = {2, 4, 1, 3, 5, 2, 3, 6, 4};  // see below for arr
  int len = sizeof(arr) / sizeof(int);
  for (int i = len - 1; i >= 0; i--) {
    for (int j = 0; j <= i; j++) {
      if (arr[j] < arr[j + 1]) {
        swap(&arr[j], &arr[j + 1]);
      }
    }
  }
  for (int m = 0; m < len; m++) {
    printf("%d\t", arr[m]);
  }
  return 0;
}

when my array is like : int arr[]={2,4,1,3,5,2,6,10}; it's sorting perfectly but when i increase the number of values in arr by one , it starts giving garbage value.

ex : int arr[]={2,4,1,3,5,2,6,10,13}; output : int arr[]={2,4,1,3,5,2,6,10};

Detailed Anwer Highly Appreciated

Answer 1

When j=i and i=len-1 (which is allowed in the loop over j) the check:

        if(arr[j]<arr[j+1]){
            swap(&arr[j],&arr[j+1]);
        }

goes out of bounds for arr. Additionally even for smaller values of i the last check is not needed. To fix your code make the loop condition j < i instead of j <= i.