根据输入的N，随机生成N个数，然后输入查找元素，在数组中进行二分查找，找到返回位置，未找到返回0，(主要表达二分查找思路，所以省略了对数组元素的排序，直接调用了库函数sort（）)。

代码如下:

#include <iostream>
#include<stdlib.h>
#include<algorithm>
using namespace std;

int a[1000];

//二分查找
int Search_Bin ( int a[], int key,int n ) {
   int low, high, mid;
   low = 1;  high = n;
   while (low <= high) {
      mid = (low + high) / 2;
     // cout << "a["<< mid <<"]=" << a[mid] << endl;
      if (key == a[mid]) return mid;
      else if (key < a[mid]) high = mid - 1;
      else low = mid + 1;
   }
   return 0;
}

//输出数组的数据
void show(int n)
{
    for(int i = 1;i<=n;++i){
        cout << a[i] << " ";
        if(i % 5 == 0)
            cout << endl;
    }
    cout << endl;
}

int main()
{
    int n; //生成个数
    int search;//带查找的数据
    cout << "请输入序列的个数:\n";
    cin >> n;
    for(int i = 1;i<=n;++i)
        a[i] = rand()%200+1;
    cout << "随机生成的序列是:\n";
    //先排序才能二分查找
    sort(a,a+n);
    show(n);
    cout << "请输入要查找的数字:\n";
    cin >> search;
    int result = 0;//查找结果 默认未找到为 0
    result = Search_Bin(a,search,n);
    if(result == 0) cout << "查找数据不存在！\n";
    else cout << "查找数据位于第" << result << "个位置\n";
    return 0;
}

注:排序函数sort（）要用到<algorithm>头文件 

运行结果: