variant_numbers.cpp

variant_numbers.cpp

#include <variant>
#include <string>
#include <vector>
#include <exception>
#include <functional>
#include <iostream>

using namespace std;

void numToStringNum(variant<int, string>& x)
{
    static vector<string> names = {
        "zero", "one", "two", "three", "four", "five", "six", "seven"  
    };
    int ix = get<int>(x);
    if(ix < 0 || ix >= (int)names.size()) {
        x = "unknown";
    }
    else {
        x = names[ix];
    }
}

int main()
{
    vector<variant<int, string>> numbers = {0, 1, 2, 4, 8};
    for_each(numbers.begin(), numbers.end(), numToStringNum);
    for_each(numbers.begin(), numbers.end(), [](auto& a){ visit([](auto& a){cout << a << endl;}, a); });

    return 0;
}

Output:

zero
one
two
four
unknown