返回数组引用的4种函数写法

#include <iostream>
#include <string>

using namespace std;

//传入的参数是数组的引用，返回值也是数组的引用
string (&fun(string (&s)[10]))[10]
{
    return s;

}

//using str_arr = string (&)[10];
/*
typedef string str_arr[10];
str_arr &fun1(str_arr &s){
　　return s;
}
*/

typedef string (&str_arr)[10];
str_arr fun1(str_arr s) {
    return s;
}

auto fun2(string (&s)[10])  -> string (&)[10]
{
    return s;
}


string d[10];
decltype(d) &fun3(decltype(d) &s)
{
    return s;
}


int main(int argc, char *argv[])
{
    string s[10] = { "1", "2", "3", "4", "5", "6", "7", "8", "9", "1"};
    decltype(s) &ds = fun(s);
    //decltype(s) &ds = fun1(s);
    //decltype(s) &ds = fun2(s);
    //decltype(s) &ds = fun3(s);
    ds[1] = "han";
    for (const auto &a : s)
    {
        cout << a << endl;
    }
    cout << endl;

    return 0;
}