#include<iostream>
#include<string>
#include <algorithm>
#include <vector>
#include <memory>
using namespace std;
int da()
{
    int n, max, b = 0, l = 2;
    cout << "有几个数";
    cin >> n;
    if (n < 2)
    {
        cout << "请尊重程序员，谢谢" << endl;
        system("pause");
        system("cls");
        return 1;
    }
    vector<double> a(n);
    for (b = 0; b < n; b++)
    {
        cout << "请输入第" << b + 1 << "个数";
        cin >> a[b];
    }
    max = a[0];
    for (b = 1; b < n; b++)
    {
        if (a[b] > max)
        {
            max = a[b];
            l = b;
        }
    }
    cout << "最大的数是" << max << "是第" << l + 1 << "个";
    while (true)
    {
        NULL;
    }
    return 0;
}

int main()
{
    const double i = 1.2;
    cout << "求最大/小数，作者：万致远 版本" << i << endl;
    char da_xiao;
    cin >> da_xiao;
    switch (da_xiao)
    {
    case '大':da(); break;
    case '小':cout << "新功能正在开发中，请等待。"; break;
    }
}char类型不能是中文，怎么办？

有点不太懂，可以在讲一下吗？

改好了，用字符串+if语句
void xiao()
{
    int n, min, b = 0, l = 2;
    cout << "有几个数";
    cin >> n;
    if (n < 2)
    {
        cout << "请尊重程序员，谢谢" << endl;
        system("pause");
        system("cls");

    }
    vector<double> a(n);
    for (b = 0; b < n; b++)
    {
        cout << "请输入第" << b + 1 << "个数";
        cin >> a[b];
    }
min = a[0];
    for (b = 1; b < n; b++)
    {
        if (a[b] < min)
        {
            min = a[b];
            l = b;
        }
    }
    cout << "最"; Sleep(500); cout << "小"; Sleep(500); cout << "的"; Sleep(500); cout << "数"; Sleep(500); cout << "是"; Sleep(500); cout << min;
    while (true)
    {
        NULL;
    }
}
int main()
{
    const double i = 1.2;
    cout << "正在加载中，请稍后。就一杯茶的功夫";
    Sleep(10000);
    cout << "求最大/小数，作者：万致远 版本" << i << endl;
    string da_xiao;
    cout << "求大？求小？";
    cin >> da_xiao;
    if (da_xiao=="大")
    {
        da();
    }
    else
    {
        if (da_xiao=="小")
        {
            xiao();
        }
        else
        {
            cout << "新功能正在开发中，或请更新版本";
        }
    }
}