#include<stdio.h>
#include<stdlib.h>
#define N 5
int binarySearch(int *x,int n,int item);
int main()
{
    int a[N]={2,7,19,45,66};
    int i,index,key;
    printf("数组a中的数据:n");
    for(i=0;i<N;i++)
        printf("%d ",a[i]);
    printf("n");
    printf("输入待查找的数据项:");
    scanf_s("%d",&key);
    index=binarySearch(a,N,key);
    if(index>=0)
        printf("%d在数组中，下标为%dn",key,index);
    else
        printf("%d不在数组中n",key);
    system("pause");
    return 0;
}
int binarySearch(int *x,int n,int item)
{
    int low,high,mid;
    low=0;
    high=n-1;
    while(low<=high)
    {
        mid=(low+high)/2;
        if(item==*(x+mid))
            return mid;
        if(item<*(x+mid))
            high=mid-1;
        if(item>*(x+mid))
            low=mid+1;
    }
    return -1;
}