利用函数进行二分法查找

#include<stdio.h>
int binary_search(int arr[],int key,int left,int right)//先定义二分查找的函数
{
while(left<=right)
{
int mid = left+((right-left)>>1);

if(key > arr[mid])
{
left = mid+1;
}
else if(key < arr[mid])
{
right = mid-1;
}
else
{
return mid;
}
}
return -1;

}
int main()
{
int arr[]={1,2,3,4,5,6,7,8,9,10};//定义一个数组
int key = 4;//在数组中找的目标数

int sz = sizeof(arr)/sizeof(arr[0]);//数组中有多少个元素

int ret = binary_search(arr,key,0,9);//定义一个接收变量接收返回值

if(ret==-1)
{
printf("找不到\n");
}
else
{
printf("找到了: %d\n",ret);
}

return 0;
}