C/C++ :: Get Volume Of A Box Using Classes

n the requirements it says this;

-create a get and set for height, width, length.
-A default parameterized constructor = 1
-A method to resize the box
-A method to get the volume of the box
-A method to convert the object to a string

My Questions:

The 3 parts I am confused by are the default parameter constructor, the re-size the box and the method to convert to string. For the default parameter part I figured making length, width and height = to 1 would work, but I'm pretty sure thats not what I'm supposed to do.

This is the main file

#include "box_class.h"
#include <iostream>
using namespace std;
int main() {
double length;
double width;
double height;
double volume;

[Code] ......