public class Var {

    public static void main (String[] args) {

	int width;   // Declare a variable
	width = 10;  // and initialize in two lines

	int height = 20; // Do both in one line

	int area;
	area = width + height;

	System.out.println();
	System.out.println("Width is " + 10);       // Role of " and "
	System.out.println("Height is " + height);  // Role of +

	System.out.println("Area of a rectangle with two sides 10" +
			   " and " + height + " is " + area);


	// Now, let's scale (enlarge) the rectangle:
	int xScaleFactor = 2;
	int yScaleFactor = 3;
	width = width * xScaleFactor;
	height = height * yScaleFactor;
	area = width * height;
	System.out.println("\nArea of a rectangle with two sides 10" +
			   " and " + height + " is " + area);

    }

}

/*

 - width, height, area, xScaleFactor, yScaleFactor are called variables.

 - You can assignment a value to a variable

 - You can update the value of a variable as many times as you want

 - The '=' operator is called the 'assignment operator', meaning you can
   assign a value to a variable using the operator.

 - 'area = width + height;' is an example of assignment statement.

   How many assignment statements are there in the main function above?

 - The grammar of an assignment statement is the following:

    <identifier> = <expression>;

   . This means: an identifier followed by '=' followed by an expression
     followed by a semicolon (;).

   . The variables width, height, area, xScaleFactor, and yScaleFactor are
     identifiers.  We don't call Var a variable because we can't change
     the value of it as we can change the value of width - as many times
     as we want even.

   . Expression is something that has a value.  That is, if you evaluate an
     expression, it produces a value.  34 is an expression since it produces
     the number 34 as a value.  4 + 5 is an expression that produces the value
     9.  x + y is an expression if x and y are valid variables with values.
     For example, if x's value is 3 and y's value is 2 then x + y evaluates to
     5.  I will say more about expressions in class.

 - The variable width is said to be of type 'int' (short for integer)

   . That means that you can assign only an integer as a value of width.


 - Note how I used System.out.println();

 - Note how I used '\n' in the System.out.println...

*/