Chapter 14, Problem 1RQE

Describe the difference between an instance member variable and a static member variable.

Explanation of Solution

Difference between instance member variable and static member variable:

Instance member variable	Static member variable
In object-oriented programming, the data field in the class is known as instance data field or instance member variable.	In object-oriented programming, the member variable which is declared with the keyword “static” is called as static member variable.
Every instance of the class has its individual copies of the class instance variables.	The keyword “static” means in memory there is only one copy of the static member variable is available.
Without disturbing any other instances, one object instance can change the values of its instance variables.	If no initialization is present, all static variables are set to zero when the first object is created.
In class, all the methods use the instance variables unless it is declared as a static.	The static member variables can be re-declared and reuse outside the class using the scope resolution operator (::).
Example: Rectangle b1, b2; //set the width and length of the "b1" b1.setwidth (4); b1.setlength (1); //set the width and length of the "b2" b2.setwidth (50); b2.setlength (20); Here, “b1” and “b2” are the instance variables.	Example: static int value;