折半查找法

//折半查找法
#include<stdio.h>
#include<stdlib.h>
int binsearch(int x,int v[],int n)
{
int low,high,mid;
low=0;
high=n-1;
while(low<=high)
{
mid=(low+high)/2;
if(x>v[mid])
low=mid+1;
else if(x<v[mid])
high=mid-1;
else
return mid;
}
return -1;
}
int main()
{
int x,n;
int position;
int v[10]={1,2,3,4,5,6,7};
//scanf("%d",x);
//scanf("%d",n);
x=2;n=7;
position=binsearch(x,v,n);//调用函数时，不要再参数的类型，数组v[],用V代替就好。
printf("%d\n",position);
system("pause");
return 0;

}

while循环中只用一次测试

//折半查找法,可读性较差
#include<stdio.h>
#include<stdlib.h>
int binsearch(int x,int v[],int n)
{
int low,high,mid;
low=0;
high=n-1;
mid=(low+high)/2;
while(low<=high)
{

if (x>v[mid])
low=mid+1;
else 
high=mid-1;
mid=(low+high)/2;
}
if  (x==v[mid])
return mid;
else
return -1;
}
int main()
{
int x=0,n=0;
int position;
int v[10]={1,2,3,4,5,6,7};//数组初始化
//scanf("%d",x);
//scanf("%d",n);
x=7;n=7;
position=binsearch(x,v,n);//调用函数时，不要再参数的类型，数组v[],用V代替就好。
printf("%d\n",position);
system("pause");
return 0;
}