/*

 * BinarySearch.c

 *

 *  Created on: 2014年6月25日

 *      Author: wenbo

 */

#include <stdio.h>

int binarySearch(int arr[],int num,int length){

	int l = 0,u = length-1;

	int curr = 0;

	while(l<=u){

		curr = (u+l)/2;

		if(arr[curr]==num){

			printf("index of the num is:%d\n",curr);

			return curr;

		}

		if(arr[curr]<num){

			l = curr+1;

		}

		if(arr[curr]>num){

			u = curr-1;

		}

	}

	printf("can't find the number.\n");

	return -1;

}

int main(){

	int a[10] = {1,2,3,4,5,65,77,88,99,1001};

	binarySearch(a,1,10);

	binarySearch(a,65,10);

	binarySearch(a,1001,10);

	binarySearch(a,100,10);

	return 0;

}