函数二分法查下标

#include<stdio.h>
int xiabiao(int *arr,int size, int num)
{
int left=0;
int right=size-1;
int mid;
while(left<=right){
mid=(left+right)/2;
if(num<arr[mid]){
right=mid-1;
}
else if (num>arr[mid]){
left=mid+1;
}
else return mid;
}return -1;
}
int main()
{
int arr[]={1,2,3,4,5,6,7,8,9};
int size;
size=sizeof(arr)/sizeof(arr[0])-1;
printf(“下标是%d”,xiabiao(arr,size,3));
}

来源：CSDN

作者：wwwwwmk

链接：https://blog.csdn.net/wwwwwmk/article/details/103244426