queue::emplace() in C++ STL
Last Updated :
21 Oct, 2020
Queue is also an abstract data type or a linear data structure, which follows a particular order in which the operations are performed. The order is First In First Out (FIFO). In a FIFO data structure, the first element added to the queue will be the first one to be removed.
queue::emplace()
This function is used to insert a new element into the queue container, the new element is added to the end of the queue.
Syntax :
queuename.emplace(value)
Parameters :
The element to be inserted into the queue
is passed as the parameter.
Result :
The parameter is added to the
forward list at the end.
Examples:
Input : myqueue{1, 2, 3, 4, 5};
myqueue.emplace(6);
Output : myqueue = 1, 2, 3, 4, 5, 6
Input : myqueue{};
myqueue.emplace(4);
Output : myqueue = 4
Errors and Exceptions
1. It has a strong exception guarantee, therefore, no changes are made if an exception is thrown.
2. The parameter should be of the same type as that of the container otherwise, an error is thrown.
CPP
#include <iostream>
#include <queue>
using namespace std;
int main()
{
queue<int> myqueue;
myqueue.emplace(1);
myqueue.emplace(2);
myqueue.emplace(3);
myqueue.emplace(4);
myqueue.emplace(5);
myqueue.emplace(6);
while (!myqueue.empty())
{
cout << ' ' << myqueue.front();
myqueue.pop();
}
return 0;
}
|
Output:
1 2 3 4 5 6
CPP
#include <iostream>
#include <queue>
using namespace std;
int main()
{
queue<char> myqueue;
myqueue.emplace('k');
myqueue.emplace('j');
myqueue.emplace('y');
myqueue.emplace('r');
myqueue.emplace('y');
myqueue.emplace('u');
while (!myqueue.empty())
{
cout << ' ' << myqueue.front();
myqueue.pop();
}
return 0;
}
|
Output:
k j y r y u
CPP
#include <iostream>
#include <queue>
using namespace std;
int main()
{
queue<string> myqueue;
myqueue.emplace("This");
myqueue.emplace("is");
myqueue.emplace("a");
myqueue.emplace("computer");
myqueue.emplace("science");
myqueue.emplace("portal");
while (!myqueue.empty())
{
cout << ' ' << myqueue.front();
myqueue.pop();
}
return 0;
}
|
Output:
This is a computer science portal
Time Complexity: O(1)
Application: Input an empty queue and find the sum of the elements of the queue.
Input : 7, 6, 4, 2, 7, 8
Output : 34
Algorithm
1. Insert elements into the queue using emplace() function.
2. Check if a queue is empty, if not add the front element to the sum variable and pop it.
3. Keep repeating this step until the queue becomes empty
4. Print the sum variable.
CPP
#include <queue>
#include <iostream>
using namespace std;
int main()
{
int sum = 0;
queue<int> myqueue{};
myqueue.emplace(7);
myqueue.emplace(6);
myqueue.emplace(4);
myqueue.emplace(2);
myqueue.emplace(7);
myqueue.emplace(8);
while (!myqueue.empty()) {
sum = sum + myqueue.front();
myqueue.pop();
}
cout<< sum;
}
|
Output
34