code. compile. run. debug. share.
Source Code
Language
#include <variant>
#include <string>
#include <iostream>
using Variant = std::variant<double, std::string>;
// helper type for the visitor
template<class... Ts> struct overloaded : Ts... { using Ts::operator()...; };
// explicit deduction guide (not needed as of C++20)
template<class... Ts> overloaded(Ts...) -> overloaded<Ts...>;
std::string_view string_from(const Variant& v)
{
static std::string buffer;
return std::visit(overloaded {
[&buffer](const double arg) -> std::string_view { buffer = std::to_string(arg); return buffer; },
[](const std::string& arg) -> std::string_view { return arg; },
}, v);
}
int main()
{
Variant v1 {"Hello"};
Variant v2 {1.23};
std::cout << string_from(v1) << '\n';
std::cout << string_from(v2) << '\n';
return 0;
}
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