Tuples in C++

Difficulty Level : Easy
Last Updated : 26 Jun, 2020

What is a tuple?
A tuple is an object that can hold a number of elements. The elements can be of different data types. The elements of tuples are initialized as arguments in order in which they will be accessed.

Operations on tuple :-

1. get() :- get() is used to access the tuple values and modify them, it accepts the index and tuple name as arguments to access a particular tuple element.

2. make_tuple() :- make_tuple() is used to assign tuple with values. The values passed should be in order with the values declared in tuple.

// C++ code to demonstrate tuple, get() and make_pair()
#include<iostream>
#include<tuple> // for tuple
using namespace std;
int main()
{
    // Declaring tuple
    tuple <char, int, float> geek;
  
    // Assigning values to tuple using make_tuple()
    geek = make_tuple('a', 10, 15.5);
  
    // Printing initial tuple values using get()
    cout << "The initial values of tuple are : ";
    cout << get<0>(geek) << " " << get<1>(geek);
    cout << " " << get<2>(geek) << endl;
  
    // Use of get() to change values of tuple
    get<0>(geek) = 'b';
    get<2>(geek) =  20.5;
  
     // Printing modified tuple values
    cout << "The modified values of tuple are : ";
    cout << get<0>(geek) << " " << get<1>(geek);
    cout << " " << get<2>(geek) << endl;
  
    return 0;
}

Output:

The initial values of tuple are : a 10 15.5
The modified values of tuple are : b 10 20.5

In the above code, get() modifies the 1st nd 3rd value of tuple.

3. tuple_size :- It returns the number of elements present in the tuple.

//C++ code to demonstrate tuple_size
#include<iostream>
#include<tuple> // for tuple_size and tuple
using namespace std;
int main()
{
  
    // Initializing tuple
    tuple <char,int,float> geek(20,'g',17.5);
  
    // Use of size to find tuple_size of tuple
    cout << "The size of tuple is : ";
    cout << tuple_size<decltype(geek)>::value << endl;
  
    return 0;
  
}

Output:

The size of tuple is : 3

4. swap() :- The swap(), swaps the elements of the two different tuples.

//C++ code to demonstrate swap()
#include<iostream>
#include<tuple> // for swap() and tuple
using namespace std;
int main()
{
  
    // Initializing 1st tuple
    tuple <int,char,float> tup1(20,'g',17.5);
      
    // Initializing 2nd tuple
    tuple <int,char,float> tup2(10,'f',15.5);
      
    // Printing 1st and 2nd tuple before swapping
    cout << "The first tuple elements before swapping are : ";
    cout <<  get<0>(tup1) << " " << get<1>(tup1) << " "
         << get<2>(tup1) << endl;
    cout << "The second tuple elements before swapping are : ";
    cout <<  get<0>(tup2) << " " << get<1>(tup2) << " " 
         << get<2>(tup2) << endl;
      
    // Swapping tup1 values with tup2
    tup1.swap(tup2);
      
    // Printing 1st and 2nd tuple after swapping
    cout << "The first tuple elements after swapping are : ";
    cout <<  get<0>(tup1) << " " << get<1>(tup1) << " " 
         << get<2>(tup1) << endl;
    cout << "The second tuple elements after swapping are : ";
    cout <<  get<0>(tup2) << " " << get<1>(tup2) << " " 
         << get<2>(tup2) << endl;
  
    return 0;
}

Output:

The first tuple elements before swapping are : 20 g 17.5
The second tuple elements before swapping are : 10 f 15.5
The first tuple elements after swapping are : 10 f 15.5
The second tuple elements after swapping are : 20 g 17.5

5. tie() :- The work of tie() is to unpack the tuple values into separate variables. There are two variants of tie(), with and without “ignore” , the “ignore” ignores a particular tuple element and stops it from getting unpacked.

// C++ code to demonstrate working of tie()
#include<iostream>
#include<tuple> // for tie() and tuple
using namespace std;
int main()
{   
    // Initializing variables for unpacking
    int i_val;
    char ch_val;
    float f_val;   
      
    // Initializing tuple
    tuple <int,char,float> tup1(20,'g',17.5);
  
    // Use of tie() without ignore
    tie(i_val,ch_val,f_val) = tup1;
      
    // Displaying unpacked tuple elements
    // without ignore
    cout << "The unpacked tuple values (without ignore) are : ";
    cout << i_val << " " << ch_val << " " << f_val;
    cout << endl;
      
    // Use of tie() with ignore
    // ignores char value
    tie(i_val,ignore,f_val) = tup1;
      
    // Displaying unpacked tuple elements
    // with ignore
    cout << "The unpacked tuple values (with ignore) are : ";
    cout << i_val  << " " << f_val;
    cout << endl;
  
    return 0;
  
}

Output:

The unpacked tuple values (without ignore) are : 20 g 17.5
The unpacked tuple values (with ignore) are : 20 17.5

6. tuple_cat() :- This function concatenates two tuples and returns a new tuple.

// C++ code to demonstrate working of tuple_cat()
#include<iostream>
#include<tuple> // for tuple_cat() and tuple
using namespace std;
int main()
{
    // Initializing 1st tuple
    tuple <int,char,float> tup1(20,'g',17.5);
  
    // Initializing 2nd tuple
    tuple <int,char,float> tup2(30,'f',10.5);
      
    // Concatenating 2 tuples to return a new tuple
    auto tup3 = tuple_cat(tup1,tup2);
      
    // Displaying new tuple elements
    cout << "The new tuple elements in order are : ";
    cout << get<0>(tup3) << " " << get<1>(tup3) << " ";
    cout << get<2>(tup3) << " " << get<3>(tup3) << " ";
    cout << get<4>(tup3) << " " << get<5>(tup3) << endl;
  
    return 0;
}

Output:

The new tuple elements in order are : 20 g 17.5 30 f 10.5

This article is contributed by Manjeet Singh .If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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