Defining a Class - C++ Class

Introduction

A class is a user-defined type.

The definition of a type uses the class keyword.

The basic organization of a class definition looks like this:

class ClassName
{
  // Code that defines the members of the class...
};

All the members of a class are private by default.

Private members cannot be accessed from outside the class.

You use the public keyword followed by a colon to mark public members.

public and private are access specifiers for the class members.

Here's how an outline class looks with access specifiers:

class ClassName
{
  private:
  // Code that specifies members that are not accessible from outside the class...

  public:
  // Code that specifies members that are accessible from outside the class...
};

A function member can reference any other member of the same class.

Demo Code

#include <iostream>

class Pool {/*from   w w w  .  ja  v  a2  s .  co m*/
public:
  double length{ 1.0 };
  double width{ 1.0 };
  double height{ 1.0 };

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

int main() {
  Pool myPool;                                  // A Pool object with all dimensions 1
  std::cout << "Volume of myPool is" << myPool.volume() << std::endl;  // Volume is 1.0
  myPool.length = 1.5;
  myPool.width = 2.0;
  myPool.height = 4.0;
  std::cout << "Volume of myPool is" << myPool.volume() << std::endl;  // Volume is 12.0

}

Defining a Class - C++ Class

Introduction

Demo Code

Result

Related Tutorials