Multimap Find In C++ STL

As we all know, the C++ programming language has many in-built functions to help us avoid writing long lines of code. One such function is the multimap find function available in the rich library of C++ programming language, the Standard Template Library(STL). It will help us return an iterator which refers to or points to the position of the key containing the data traversal in the long or small multimap we have created. Suppose you have a different objective of knowing all the fundamental data values. In that case, you can refer to the equal range function available for us in the rich library of C++ programming language, the Standard Template Library(STL).

Multimap in C++

Example


// Here we are writing down the C++ programming language code to 
// demonstrate
// the concept of multimap find() in C++ STL(Standard Template Library)

#include <iostream>
#include <iterator>
#include <map>

using namespace std;
// The main driver code functionality starts from here!
int main()
{
    // Here, we are trying to create an initialiser container 
	// which will help us with creating a multimap using C++ STL
	multimap<int, int> gquiz1;

     // these insert functions which we have written below help us
	// with creating a multimap holding the values inserted below!

	gquiz1.insert(pair<int, int>(1, 40));
	gquiz1.insert(pair<int, int>(2, 30));
	gquiz1.insert(pair<int, int>(3, 60));
	gquiz1.insert(pair<int, int>(6, 50));
	gquiz1.insert(pair<int, int>(6, 10));

	 // elements which we are going to display on the Output screen are
	multimap<int, int>::iterator itr;
	cout << "\nThe multimap gquiz1 is : \n";
	cout << "\tKEY\tELEMENT\n";
	// here we are writing the for loop, which contains the auto code
	// functionality containing the find() function at different positions
	for (itr = gquiz1.begin(); itr != gquiz1.end(); ++itr) {
		cout << '\t' << itr->first
			<< '\t' << itr->second << '\n';
	}
	cout << endl;

	// here, we are trying to add elements randomly,
	// as it helps us to check the sorted keys property in C++ STL
	gquiz1.insert(pair<int, int>(4, 50));
	gquiz1.insert(pair<int, int>(5, 10));

	// the below code helps us with printing multimap gquiz1 again

	cout << "\nmultimap quiz1 after"
		<< " adding the extra elements is : \n";
	cout << "\tkey\telement\n";
	for (itr = gquiz1.begin(); itr != gquiz1.end(); ++itr) {
		cout << '\t' << itr->first
			<< '\t' << itr->second << '\n';
	}
	cout << endl;

	// the below code snippet below assigning the elements from quiz1 to quiz2
	multimap<int, int> gquiz2(gquiz1.begin(),
							gquiz1.end());

// the below code snippet prints all the elements of the multimap gquiz2
	cout << "\nThe multimap gquiz2 after"
		<< " assign from gquiz1 is : \n";
	cout << "\tKEY\tELEMENT\n";
	for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) {
		cout << '\t' << itr->first
			<< '\t' << itr->second << '\n';
	}
	cout << endl;

	// here, we are trying to remove all elements up to
	// key with the value 3 in quiz2
	cout << "\n the quiz2 after the removal of"
		<< " elements less than key = 3 : \n";
	cout << "\t key \t element \n";
	gquiz2.erase(gquiz2.begin(), gquiz2.find(3));
	for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) {
		cout << '\t' << itr->first
			<< '\t' << itr->second << '\n';
	}

	// the below code helps us with removing all the elements with key = 4
	int num;
	num = gquiz2.erase(4);
	cout << "\n quiz 2.erase(4) : ";
	cout << num << " removed \n";
	cout << "\tkey\telement\n";
	for (itr = gquiz2.begin(); itr != gquiz2.end(); ++itr) {
		cout << '\t' << itr->first
			<< '\t' << itr->second << '\n';
	}

// new line printing statement the endl statement
	cout << endl;

	// the lower and upper bounds of the much awaited 
	// for multimap gquiz1 key = 5
	cout << "the quiz1.lower bound (5) : "
		<< "\tkey = ";
	cout << gquiz1.lower_bound(5)->first << '\t';
	cout << "\telement = "
		<< gquiz1.lower_bound(5)->second
		<< endl;
	cout << "the quiz1.upper bound (5): "
		<< "\tKEY = ";
	cout << gquiz1.upper_bound(5)->first << '\t';
	cout << "\telement = "
		<< gquiz1.upper_bound(5)->second
		<< endl;

	return 0;
	// The main driver code functionality ends from here!
}

Output:

Output


The multimap gquiz1 is : 
	KEY	ELEMENT
	1	40
	2	30
3	60
	6	50
	6	10

Multimap quiz1 after adding the extra elements is : 
	key	element
	1	40
	2	30
	3	60
	4	50
	5	10
	6	50
	6	10

The multimap gquiz2 after assignment from gquiz1 is : 
	KEY	ELEMENT
	1	40
	2	30
	3	60
	4	50
	5	10
	6	50
	6	10

 quiz2 after the removal of elements less than key = 3 : 
	 key 	 element 
	3	60
	4	50
	5	10
	6	50
	6	10

 quiz 2.erase(4) : 1 removed 
	key	element
	3	60
	5	10
	6	50
	6	10

the quiz1.lower bound (5) : 	key = 5		element = 10
the quiz1.upper bound (5) : 	KEY = 6		element = 50