Binary Search

binary-search.c

int binarySearch(char *list[ ], char target[ ], int n)‏
{
	int start, end, middle;
	start = 0;
	end = n - 1;
	while (start <= end)‏
	{
		middle = (start + end) / 2;
		if (strcmp(target, list[middle]) < 0)‏
		{
			end = middle - 1;
		}
		else
		if (strcmp(target, list[middle) > 0)‏
		{
			start = middle + 1;
		}
		else
		{
			return middle;
		}
	}	//  end while
	return -1;
}	//  end binary search

Binary search is much faster than linear search.

For an ordered list of N entries, linear search requires a maximum of N array accesses, and binary search requires a maximum of log2 N (rounded up).