C++ Usage and Example of Queue size() Function

C++ STL Queue (Queue)

C++ The queue size() function returns the number of elements in the queue.

Syntax

size_type size() const;

Parameters

This function takes no parameters and returns the size of the queue.

Return value

Returns the number of elements in the queue. In other words, it gives the size of the queue.

Instance1

Example

#include <iostream>
#include <queue>
int main()
{
	std::queue<int> newqueue;
	std::cout << "0. size: " << newqueue.size();
	for(int j=0;5; j++)
	newqueue.push(j);
	std::cout << "\n";
	std::cout << "1. size: " << newqueue.size();
	newqueue.pop();
	std::cout << "\n";
	std::cout << "2. size: "<< newqueue.size();
	return 0;
}

Output:

0.size: 0
1.size:　5
2.size:　4

Instance2

Example

#include <iostream>
#include <queue>
using namespace std;
int main()
{
	int result = 0;
	queue<int> newqueue;
	newqueue.push(12);
	newqueue.push(24);
	newqueue.push(36);
	newqueue.push(48);
	cout << "queue size is ";
	cout << newqueue.size();
	return 0;
}

Output:

The size of queue is　4

Complex

The complexity is constant.

Data Rivalry

This function accesses the container. By accessing the container, the size of the queue can be evaluated.

Exception Safety

It provides the same guarantees as operations performed on underlying container objects.

C++ STL Queue (Queue)