Pair
Pair in C++ STL is used to combine two values having different or same data types. It provides a way to store two different values as a single element. The individual values of a pair can be accessed through its public members first and second.
To use STL built-in pair, you need to include <utility> header.
Code Implementation
//
// main.cpp
// Pair
//
// Created by Himanshu on 11/04/22.
//
#include <iostream>
#include <utility>
#include <vector>
#include <string>
using namespace std;
int main () {
//Initializations
//using make_pair
pair<int, int> pairRank = make_pair(1, 98);
//using value init
pair<int, string> pairNameFirst (1, "Anon");
//using copy constructor
pair<int, string> pairTemp(pairNameFirst);
cout<<"pairRank values:"<<endl;
cout<<pairRank.first<<", "<<pairRank.second<<endl;
//accessing pair elements using method get<>
cout<<"pairNameFirst values:"<<endl;
cout<<get<0>(pairNameFirst)<<", "<<get<1>(pairNameFirst)<<endl<<endl;
vector<pair<int, int>> pairRankVector;
vector<pair<int, string>> pairNameVector;
vector<pair<int, int>>::iterator rankItr;
vector<pair<int, string>>::iterator nameItr;
pairRankVector.push_back(pairRank);
pairNameVector.push_back(pairNameFirst);
vector<int> rankMarks = {95, 90, 87, 83, 75};
vector<string> rankNames = {"Bruw", "Cync", "Droke", "Elph", "Frel"};
int n = (int) rankMarks.size();
for (int i=0; i<n; i++) {
pairRankVector.push_back(make_pair(i+2, rankMarks[i]));
pairNameVector.push_back(make_pair(i+2, rankNames[i]));
}
cout<<"Size of pairRankVector: "<<pairRankVector.size()<<endl<<endl;
//accessing vector elements using iterator,
//accessing pair elements using -> operator
//accessing vector element using (*iterator)
for (rankItr = pairRankVector.begin(), nameItr = pairNameVector.begin();
rankItr != pairRankVector.end(); rankItr++, nameItr++) {
cout<<rankItr->first<<" "<<nameItr->second<<" "<<(*rankItr).second<<endl;
}
return 0;
}
Output
pairRank values: 1, 98 pairNameFirst values: 1, Anon Size of pairRankVector: 6 1 Anon 98 2 Bruw 95 3 Cync 90 4 Droke 87 5 Elph 83 6 Frel 75
Here’s a working example: Pair
Tuple
Tuple unlike pair can be used to combine two or more than two values having different or same data types.
To use STL built-in tuple, you need to include <tuple> header.
Code Implementation
//
// main.cpp
// Tuple
//
// Created by Himanshu on 11/04/22.
//
#include <iostream>
#include <tuple>
#include <vector>
#include <string>
using namespace std;
int main () {
//Initializations
//using make_tuple
tuple<int, string, int> tupleFirst = make_tuple(1, "Anon", 98);
//using value init
tuple<int, string, int> tupleLast (7, "Glee", 67);
//using copy constructor
tuple<int, string, int> tupleTemp(tupleLast);
cout<<"tupleTemp values:"<<endl;
cout<<get<0>(tupleTemp)<<", "<<get<1>(tupleTemp)<<", "<<get<2>(tupleTemp)<<endl<<endl;
vector<int> rankMarks = {95, 90, 87, 83, 75};
vector<string> rankNames = {"Bruw", "Cync", "Droke", "Elph", "Frel"};
vector<tuple<int, string, int>> nameList;
nameList.push_back(tupleFirst);
int n = (int) rankMarks.size();
for (int i=0; i<n; i++) {
nameList.push_back(make_tuple(i+2, rankNames[i], rankMarks[i]));
}
nameList.push_back(tupleLast);
cout<<"Size of (vector) nameList: "<<nameList.size()<<endl<<endl;
for (tuple<int, string, int> t: nameList) {
cout<<get<0>(t)<<" "<<get<1>(t)<<" "<<get<2>(t)<<endl;
}
return 0;
}
Output
tupleTemp values: 7, Glee, 67 Size of (vector) nameList: 7 1 Anon 98 2 Bruw 95 3 Cync 90 4 Droke 87 5 Elph 83 6 Frel 75 7 Glee 67
Here’s a working example: Tuple