TO IMPLEMENT BINARY SEARCH ALGORITHM IN C

int BinarySearch(int *array, int number_of_elements, int key)
{
        int low = 0, high = number_of_elements-1, mid;
        while(low <= high)
        {
                mid = (low + high)/2;
                if(array[mid] < key)
{
                       low = mid + 1;
               }
               else if(array[mid] == key)
               {
                       return mid;
                }
                else if(array[mid] > key)
                {
high = mid-1;
               }
       }
       return -1;
}
int main()
{
int number_of_elements;
        scanf("%d",&number_of_elements);
        int array[number_of_elements];
        int iter;
        for(iter = 1;iter < number_of_elements;iter++)
        {
if(array[iter] < array[iter - 1])
                {
                        printf("Given input is
not sorted\n");
return 0;
                }
        }
        int key;
        scanf("%d",&key);
        /* Calling this functions searches for the key and returns its index. It returns -1          if key is not found.*/
        int index;
index = BinarySearch(array,number_of_elements,key);
        if(index==-1)
        {
                printf("Element not found\n");
      }
       else
       {
               printf("Element is at index %d\n",index);
        }
return 0;
}