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

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

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

The function returns the current size of the stack.

Syntax

stack<T> st; //declaration
int st.size();

Parameter(s)

This function does not accept any parameter.

Return value

This function returns the size of stack of "int" 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.size() //2
Print temp//prints 2 which is current stack size

Example

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

int main(){
    cout<<"...use of size 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 size is: "<<st.size()<<endl; //size function
    cout<<"stack elements are:\n";
    while(!st.empty()){//stack not empty
        cout<<"top element is:"<<st.top()<<endl;//print top element
        st.pop();
        count++;
    }
    if(st.empty())
    cout<<"stack empty\n";
    cout<<"stack size is: "<<st.size()<<endl; //size function
    cout<<count<<" pop operation performed total to make stack empty\n";
	
    return 0;   
}

Output

...use of size function...
stack size is: 3
stack elements are:
top element is:6
top element is:5
top element is:4
stack empty
stack size is: 0
3 pop operation performed total to make stack empty