The C++Course provides a general introduction to programming in C++. It is based on A.B. Downey's book, How to Think Like a Computer Scientist. Click here for details.

Accessing Instance Variables

You can read the values of an instance variable using the same syntax we used to write them:

    int x = blank.x;

The expression blank.x means "go to the object named blank and get the value of x." In this case we assign that value to a local variable named x. Notice that there is no conflict between the local variable named x and the instance variable named x. The purpose of dot notation is to identify which variable you are referring to unambiguously.

You can use dot notation as part of any C++ expression, so the following are legal.

  cout << blank.x << ", " << blank.y << endl;
  double distance = blank.x * blank.x + blank.y * blank.y;

The first line outputs 3, 4; the second line calculates the value 25.

Last Update: 2005-12-05