std::stack top() method

since C++98

// Non const version
reference top();

// Const version
const_reference top() const;

Returns a reference

to the top element in the stack.
This element will be the first element to be removed on a call to pop().

note

Effectively calls c.back().

Parameters

(none)

Return value

Reference to the last element.

Exceptions

(none)

Complexity

Constant - (1).

Example

Main.cpp

#include <stack>
#include <iostream>

void reportStackSize(const std::stack<int>& s)
{
    std::cout << s.size() << " elements on stack\n";
}

void reportStackTop(const std::stack<int>& s)
{
    // Leaves element on stack
    std::cout << "Top element: " << s.top() << '\n';
}

int main()
{
    std::stack<int> s;
    s.push(2);
    s.push(6);
    s.push(51);

    reportStackSize(s);
    reportStackTop(s);

    reportStackSize(s);
    s.pop();

    reportStackSize(s);
    reportStackTop(s);
}

Output

3 elements on stack
Top element: 51
3 elements on stack
2 elements on stack
Top element: 6