prog12_01.cpp

一本语言类编程书籍

// Program 12.1 Using a Box class    File: prog12_01.cpp
#include <iostream>
using std::cout;
using std::endl;

// Class to represent a box
class Box {
  public:
    double length;
    double width;
    double height;

    // Function to calculate the volume of a box
    double volume() {
      return length * width * height;
    }
};

int main() {
  Box firstBox = { 80.0, 50.0, 40.0 };

  // Calculate the volume of the box
  double firstBoxVolume = firstBox.volume();
  cout << endl;
  cout << "Size of first Box object is "
       << firstBox.length  << " by "
       << firstBox.width << " by "
       << firstBox.height
       << endl;
  cout << "Volume of first Box object is " << firstBoxVolume
       << endl;

  Box secondBox = firstBox;   // Create a second Box object the same as firstBox

  // Increase the dimensions of second Box object by 10%
  secondBox.length *= 1.1;
  secondBox.width *= 1.1;
  secondBox.height *= 1.1;

  cout << "Size of second Box object is "
       << secondBox.length << " by " 
       << secondBox.width << " by "
       << secondBox.height
       << endl;
  cout << "Volume of second Box object is " << secondBox.volume()
       << endl;

  cout << "Increasing the box dimensions by 10% has increased the volume by "
       << static_cast<long>
              ((secondBox.volume()-firstBoxVolume)*100.0/firstBoxVolume)
       << "%"
       << endl;
  return 0;
}