Shorthand Operators

Certain types of arithmetic operations are performed a lot in most computer programs. These common arithmetic operations perform some arithmetic operation on the original value of a variable and then reassign the new value back to the original variable. A common example is the statement that increments a variable by 1, which is written as follows :

 Num = 10  ' Do some other stuff... Num = Num + 1    ' This increments Num by 1 

In the last statement, you take the original value of Num (that is, 10 ), add 1 to it, and then assign the new value back to Num . In short, the last statement simply increments Num by 1.

The increment statement, Num = Num + 1 , has this general form:

  Operand1  =  Operand1 ArithmeticOperator Operand2  

Because such operations are so common, Visual Basic .NET supplies shorthand operators to simplify these statements. With a shorthand operator, the increment statement can be rewritten as this:

 Num += 1 

The effect on Num is identical; its value is incremented by 1.

As you can see, the shorthand operator replaces this syntax:

  Operand1  =  Operand1 ArithmeticOperator Operand2  

with this:

  Operand1 ArithmeticOperator  =  Operand2  

The only catch is that the arithmetic shorthand operators must do the assignment into themselves . Whereas Operand2 can be a variable, a numeric constant, or another expression, Operand1 must be a variable. The shorthand operators are listed in Table 9.2.

Table 9.2. Shorthand Arithmetic Operators

Shorthand Operator	Operation	Full Expression	Shorthand Expression
+=	Addition	X = X + 1	X += 1
-=	Subtraction	X = X + Y	X -= Y
*=	Multiplication	X = X * 8	X *= 8
/=	Division	X = X / 2	X /= 2
\=	Integer Division	X = X \ 3	X \= 3
^=	Exponentiation	X = X ^ 2	X ^= 2

The shorthand operators don't give you anything you didn't have before. They simply give you a shorter way to write the statements. (By the way, don't forget the shorthand operator for string concatenation, &= , for building strings.)