Tuples in C++
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.
CPP
// 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 and 3rd value of tuple.
3. tuple_size :- It returns the number of elements present in the tuple.
CPP
//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.
CPP
//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.
CPP
// 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.
CPP
// 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
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