std::tuple, std::pair | Returning multiple values from a function using Tuple and Pair in C++

2.4

There can be some instances where you need to return multiple values (may be of different data types ) while solving a problem. One method to do the same is by using pointers, structures or global variables, already discussed here
There is another interesting method to do the same without using the above methods,  using tuples (for returning multiple values ) and pair (for two values).

We can declare the function with return type as pair or tuple (whichever required) and can pack the values to be returned and return the packed set of values. The returned values can be unpacked in the calling function.

Tuple

  • A tuple is an object capable to hold a collection of elements where each element can be of a different type.
  • Class template std::tuple is a fixed-size collection of heterogeneous values

Pair

  • This class couples together a pair of values, which may be of different types
  • A pair is a specific case of a std::tuple with two elements

Note : Tuple can also be used to return two values instead of using pair .

#include<bits/stdc++.h>
using namespace std;

// A Method that returns multiple values using
// tuple in C++.
tuple<int, int, char> foo(int n1, int n2)
{
    // Packing values to return a tuple
    return make_tuple(n2, n1, 'a');             
}

// A Method returns a pair of values using pair
std::pair<int, int> foo1(int num1, int num2)
{
    // Packing two values to return a pair 
    return std::make_pair(num2, num1);            
}

int main()
{
    int a,b;
    char cc;
    
    // Unpack the elements returned by foo
    tie(a, b, cc) = foo(5, 10);      
    
    // Storing  returned values in a pair 
    pair<int, int> p = foo1(5,2);  
    
    cout << "Values returned by tuple: ";
    cout << a << " " << b << " " << cc << endl;
    
    cout << "Values returned by Pair: ";
    cout << p.first << " " << p.second;
    return 0;
}

Output:

Values returned by tuple: 10 5 a
Values returned by Pair: 2 5

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