How to return multiple values from a function in C++17
While C++ does not have an official way to return multiple values from a function, one can make use of the std::pair, std::tuple, or a local struct to return multiple values.
However, with the introduction of structured binding in C++17, the process is greatly simplified as the output parameters no longer need to be initialized.
Code
The following code snippet shows the way to return multiple values from a function using a local structure:
#include <iostream>using namespace std;auto foo() {struct retVals { // Declare a local structureint i1, i2;string str;};return retVals {10, 20, "Hi"}; // Return the local structure}int main() {auto [value1, value2, value3] = foo(); // structured binding declarationcout << value1 << ", " << value2 << ", " << value3 << endl;}
Note the structured binding syntax on line ; there is no need to instantiate output values before calling the function. The datatypes are determined automatically.
The std::tuple can also be used to return multiple values in conjunction with structured binding. This is shown below:
#include <iostream>#include <tuple>using namespace std;tuple<int, float, string> foo(){return {128, 3.142, "Hello"};}int main(){auto [value1, value2, value3] = foo();cout << value1 << ", " << value2 << ", " << value3 << endl;}
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