Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
queue::empty() and queue::size() in C++ STL
In this article we will be discussing the working, syntax and examples of queue::empty() and queue::size() functions in C++ STL.
What is a queue in C++ STL?
Queue is a simple sequence or data structure defined in the C++ STL which does insertion and deletion of the data in FIFO(First In First Out) fashion. The data in a queue is stored in continuous manner. The elements are inserted at the end and removed from the starting of the queue. In C++ STL there is already a predefined template of queue, which inserts and removes the data in the similar fashion of a queue.
What is the queue::empty()?
queue::empty() is an inbuilt function in C++ STL which is declared in
Syntax
myqueue.empty();
This function accepts no parameter
Return value
This function returns true if the size of the associated queue container is 0, else will return false.
Example
Input: queue<int> myqueue = {10, 20, 30, 40};
myqueue.empty();
Output:
False
Input: queue<int> myqueue;
myqueue.empty();
Output:
TrueExample
#include <iostream>
#include <queue>
using namespace std;
int main(){
queue<int> Queue;
Queue.push(10);
Queue.push(20);
Queue.push(30);
Queue.push(40);
//check is queue is empty or not
if (Queue.empty()){
cout<<"Queue is empty";
}
else{
cout <<"Queue is not empty";
}
return 0;
}Output
If we run the above code it will generate the following output −
Queue is not empty
What is queue::size()?
queue::size() is an inbuilt function in C++ STL which is declared in <queue> header file. queue::size() is used to check whether the size of the associated queue container. This function returns an unsigned int value, i.e the size of the queue container, or the number of elements present in a queue container. This function returns 0 if the queue is empty or having no elements in it.
Syntax
myqueue.size();
This function accepts no parameter
Return value
This function returns unsigned int, the size of the queue container associated with the function.
Example
Input: queue<int> myqueue = {10, 20 30, 40};
myqueue.size();
Output:
4
Input: queue<int> myqueue;
myqueue.size();
Output:
0Example
#include <iostream>
#include <queue>
using namespace std;
int main(){
queue<int> Queue;
Queue.push(10);
Queue.push(20);
Queue.push(30);
Queue.push(40);
cout<<"size of Queue is : "<<Queue.size();
return 0;
}Output
If we run the above code it will generate the following output −
size of Queue is : 4
4K+ Views
