Extracting vectors from a tuple

Question

I have got int s, a vector<int> , and a vector<string> in a tuple function. If there is an error when running this function, it will return a tuple of: {0, 0, {0}, {"0"}} . The int s have no errors. I have simplified this code a lot, and can't figure out why I can't use a vector in a tuple. It puts a red squiggly line under the { . Here is a much simpler version:

#include <iostream>
#include <vector>
using namespace std;


tuple<vector<int>, vector<string>> tuples()
{
    return { {0}, {"0"} };
}


int main()
{
    tuple<vector<int>, vector<string>> result = tuples();
    if (get<0>(result) == {0} && get<1>(result) == {"0"})
    {
        cout << "It worked!\n";
    }

    return 0;
}

If you can't use vectors in tuples, what is the other way around this?

Answer 1

You can't use initialiser lists {0} on the right hand side ie after the == .

You can't use vectors in tuples is a false statement.

Changing your code to:

tuple<vector<int>, vector<string>> result = tuples();
vector<int> v = {0};
vector<string> v2 = {"0"};
if (get<0>(result) == v && get<1>(result) == v2)
{
    cout << "It worked!\n";
}

Gives the desired results.

It is also worth investigating why the compiler put a squiggly red line under your code by looking at the output from the compiler.

Answer 2

Check this one :) As far as you simply can't return initializer lists(implicit constructor of vector), you can return created tuple with vector constructors(explicit).

#include <iostream>
#include <tuple>
#include <vector>
using namespace std;

std::tuple<std::vector<int>, std::vector<string>> tuples()
{
    return std::make_tuple(std::vector<int>({0}), std::vector<std::string>({"0"}));
}


int main()
{
    tuple<vector<int>, vector<string>> result = tuples();
    if (get<0>(result) == std::vector<int>{0} && get<1>(result) == std::vector<std::string>{"0"})
    {
        cout << "It worked!\n";
    }

    return 0;
}