What happens to while loop when it starts finding an element from array and the element is not found-CodePudding

int arr[] = {1,2,3,4,5};
int i = 0;
while(arr[i]<=6){
  i  ;
}

What happens to the while loop if the element is not found in the array.

As in the above example, What will happen to i as 6 is not found in the array should it incresed till infinity or it will stop at the end of array length.

CodePudding user response：

When i==5 and code attempts arr[i] the result is undefined behavior (UB) as code attempts to read beyond that array arr[].

... should it incresed till infinity or it will stop at the end of array length.

No - there is no should. It is undefined behavior (UB).

CodePudding user response：

I got the output but I have some confusion in the while loop where i is incremented.

#include <stdio.h>
void arrayTrasversal(int *arr, int n)
{
    for (int i = 0; i < n; i  )
    {
        printf("%d ", arr[i]);
    }
    printf("\n");
}
void swap(int *a,int *b){
    int temp = *a;
    *a = *b;
    *b = temp;
}
int partition(int *arr, int low, int high)
{
    int pivot = arr[low];
    int i = low   1;
    int j = high;
    do{
        while (arr[i] <= pivot)
        {
            i  ;
        }
        while (arr[j] > pivot)
        {
            j--;
        }
        if(i<j){
            swap(&arr[i],&arr[j]);
        }
    }while (i < j);
    swap(&arr[low],&arr[j]);
    return j;

}
void quickSort(int *arr, int low, int high)
{
    int partitionIndex;
    if (low < high)
    {
        partitionIndex = partition(arr, low, high);
        quickSort(arr, low, partitionIndex - 1);
        quickSort(arr, partitionIndex   1, high);
    }
}
int main()
{
    int arr[] = {2, 4, 3, 9, 1, 4, 8, 7, 5, 6};
    int n = sizeof(arr) / sizeof(int);
    arrayTrasversal(arr, n); // Before sorting
    quickSort(arr, 0, n - 1);
    arrayTrasversal(arr, n);
    return 0;
}

What happens to i in this case if it increases till last indent and not found element greater than pivot

while (arr[i] <= pivot)
        {
            i  ;
        }

Should I use another condition like this

while (arr[i] <= pivot && i<=high)
        {
            i  ;
        }