2. Core member functions #

Created Sunday 29 November 2020

• Member functions of a class can be defined in two ways:

1. Inside the class - this makes them inline, even if you don’t use the keyword.

class Box {
   public:
      double length;      // Length of a box
      double breadth;     // Breadth of a box
      double height;      // Height of a box

      double getVolume(void) {
         return length * breadth * height;
      }
};

2. Outside the class - they are normal functions. The full name of the functions must be provided, using the scope resolution operator(::).

class Box {
   public:
      double length;      // Length of a box
      double breadth;     // Breadth of a box
      double height;      // Height of a box
};
double Box::getVolume(void) {
   return length * breadth * height;
}

In C++, a class generally consists of two files:

• .h file - contains headers
• .cpp file - contains definitions

Why use two(or multiple) files #

There are many reasons:

1. ODR rule - C++ demands all entities be declared only once.
2. Big programs compile faster, i.e compile only the files that have changed.
3. Version control and collaboration is easy.
4. Headers can be used as public facing API, i.e .cpp is obfuscated in proprietary software.