Question

For a class I have to use a stack. From what I can tell I create a stack with

#include <stack>
class c1
{
    stack<Point> openstack;
};

Point is a class I created that has an x and y int value to store points for using in simple 2D graphics. The problem I’m having is that if I do

Point p = openstack.pop();

I get an error: “No suitable consturtor exists to convert from void to Point”

Point has a set function that takes a point and will use the passed point to store the x and y values but this does not work either.

Point p;
p.set(openstack.pop()); // does not work

Can someone tell me what I am doing wrong? If you need info please ask – I can give more if needed.

Answer 1

pop() doesn’t return a value. It just removes the top value. It’s declared like this:

void pop();

To get the top value you need to call top(). After that you can call pop().

Point p = openstack.top();
openstack.pop();

There are a couple reasons why pop() does not return the value popped.