binary search

                              Binary Search

 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 \n 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;
  }