C++ Stack emplace() Function Usage and Example

C++ STL Stack (Stack)

C ++The stack emplace() function adds a new element at the top of the stack above the current top element. Now, we have a stack with an existing element, and we want to insert or push a new element into the stack. For this purpose, we use this function.

Syntax

template<class... Args> void emplace(Args&&... args);

Parameters

args: The parameter forwarding is used for the parameters of constructing the new element. That is, the element specified by args will be inserted above the current top element in the stack. Now, the newly inserted element becomes the top element, and all push and pop operations are performed on it.

Return value

This function is only used to add new elements and does not return any value. Therefore, the return type of this function is void.

Instance1

//This program demonstrates the usage of the emplace function by adding two simple strings at the top of the stack and printing them.

Example

#include<iostream>
#include<stack>
#include<string>
using namespace std;
int main()
{
	stack<string> newstack;
	newstack.emplace("I am the first one");
	newstack.emplace("I am the second one");
	cout << "newstack's content: \n"
	while (!newstack.empty())
	{
		cout << newstack.top() << '\n';
		newstack.pop();
	}
	return 0;
}

Output:

newstack's content:
I am the second one
I am the first one

Instance2

//This program adds11Insert the table of, and then print them separately to demonstrate the usage of the emplace function.

Example

#include<iostream>
#include<stack>
#include<string>
using namespace std;
int main()
{
　　　　stack<string> newstack;
　　　　newstack.emplace("11");
　　　　newstack.emplace("22");
　　　　newstack.emplace("33");
　　　　newstack.emplace("44");
　　　　newstack.emplace("55");
　　　　newstack.emplace("66");
　　　　newstack.emplace("77");
　　　　newstack.emplace("88");
　　　　newstack.emplace("99");
　　　　newstack.emplace("121");
　　　　cout << "newstack's content: \n"
　　　　cout << "Table of　11";
　　　　while (!newstack.empty())
　　　　{
　　　　　　　cout << newstack.top() << '\n';
　　　　　　　　newstack.pop();
　　　　}
　　　　return 0;
}

Output:

newstack's content:　
Table of　11121
99
88
77
66
55
44
33
22
11

Instance3

//This program demonstrates the usage of the emplace function by adding two simple strings at the top of the stack and printing them.

Example

#include<iostream>
#include<stack>
#include<string>
using namespace std;
int main()
{
	stack<string> newstack;
	newstack.emplace("We can see the application of the emplace function in the stack here");
	newstack.emplace("The new element added by the function is at the top of the stack");
	while (!newstack.empty())
	{
		cout << newstack.top() << '\n';
		newstack.pop();
	}
	return 0;
}

Output:

The new element added by the function is at the top of the stack　　　　　　　　　
We can see the application of the emplace function in the stack here

Complex

A call to emplace_back was made. This function is used to insert a new element, which is done by making a single call.

Data Races

All elements existing in the stack are modified. Since the element is added to the top, the corresponding positions of all other elements also change.

Exception Safety

It provides guarantees equivalent to the operations performed on the underlying container objects.

C++ STL Stack (Stack)