CSCI 150, Spring 2003

Arithmetic Expressions

1) Numbers can be added, subtracted, multiplied and divided as you might expect:

Example:

	var 
		x, y, z: real;
	begin
		x := 2.3;
		y := 1.2;
		z := x + y;
	end;

2) You can change the value of a variable by adding, subtracting, multiplying or dividing it by another number :

	z := z + 1;		{ Add 1 to z }
	x := x * 2;		{ Multiply x by 2}
	y := y - 5;		{ subtract 5 from y}

3) Precedence:
Multiplication and Division are performed before addition or subtraction:

	x := 8 / 2 + 2;  	{Value of x is 6}
	y := 2 + 3 * 4;		{Value of y is 14}

When multiplication and division are in the same expression, the order is evaluated starting at the left and moving to the right:

	
	z := 4/2 * 2;		{division is first, final value is 4}

To change the order of operations, use parentheses:

	z := 4/(2 * 2);		{Now the multiplication is first, the final value is 1}
	x := 8/(2 + 2);		{Addition comes first, so final value is 2}