二分查找法（自定义函数）

#pragma warning(disable:4996)
#include<stdio.h>
int erfenchazhao(int  arr[],int n,int quan) //自定义的一个函数
{
  int you = quan-1;
  int zuo = 0;
  while (zuo <= you)
  {
    int zhong = (zuo + you) / 2;
    if (arr[zhong] > n)
    {
      you = zhong - 1;
    }
    else if (arr[zhong] < n)
    {
      zuo = zhong + 1;
    }
    else
    {
      return zhong;
    }
  }
  return -1;
}
int main()
{
  int n = 0;                              //想查找的数
  int arr[] = { 1,2,3,4,5,6,7,8,9,10 };
  int quan = sizeof(arr) / sizeof(arr[0]);//先在外面求好再把这个传过去
  printf("请输入你想查找的数字n(1~10)：");
  scanf("%d", &n);
  int i = erfenchazhao(arr, n, quan);     //传不了一个数组过去
  if (i == -1)
  {
    printf("找不到");
  }
  else
  {
    printf("找到了，下标是%d", i);
  }
  return 0;
}