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stack::top() function in C++ STL

C++ STL stack::top() function with example: In this article, we are going to see how to return the current top element of a stack using C++ STL?
Submitted by Radib Kar, on February 03, 2019

C++ STL - stack::top() function

The function returns the current top element of a stack. (no change in stack status)

Syntax

stack<T> st; //declaration
T st.top();

Parameter(s)

This function does not accept any parameter.

Return type

This function returns the element of "T" type.

Header file

Header file to be included:

#include <iostream>
#include <stack>
OR
#include <bits/stdc++.h>

Sample Input and Output

For a stack of integer,
stack<int> st;
st.push(4);
st.push(5);
stack content:
5 <-- TOP
4

int temp=st.top() //5
Print temp // prints 5
stack content: //same as before, it don't change stack status
5 <-- TOP
4

Example

#include <bits/stdc++.h>
using namespace std;

int main(){
    cout<<"...use of top function...\n";
    int count=0;
    stack<int> st; //declare the stack
    st.push(4); //pushed 4
    st.push(5); //pushed 5
    st.push(6);
    
    cout<<"stack elements are:\n";
    while(!st.empty()){//stack not empty
        cout<<"top element is:"<<st.top()<<endl;//print top element
        st.pop();
        count++;
    }
    cout<<"stack empty\n";
    cout<<count<<" pop operation performed total to make stack empty\n";
    return 0;   
}

Output

...use of top function...
stack elements are:
top element is:6
top element is:5
top element is:4
stack empty
3 pop operation performed total to make stack empty