Chapter 5: Operators

An operator is a basic code element that performs some operation on one or more values to create a result. The values the operator acts upon are called operands. For example, in the following statement, the operator is + (addition), the operands are B and C, and the result is assigned to the variable A:

  A = B + C 

The Visual Basic operators fall into five categories: arithmetic, concatenation, comparison, logical, and bitwise. This chapter first explains these categories and the operators they contain, and then discusses other operator issues such as precedence, assignment operators, and operator overloading. Also included are discussions of some specialized issues that arise when you work with strings and dates.

Arithmetic Operators

The following table lists the arithmetic operators provided by Visual Basic. Most programmers should be very familiar with most of them. The four operators that may need a little extra explanation are \, Mod, <<, and >>. The last two rows in the table manipulate bit values.

Open table as spreadsheet

Operator	Purpose	Example	Result
^	Exponentiation	2 ^ 3	(2 to the power 3) = 2 * 2 * 2 = 8
-	Negation	-2	-2
*	Multiplication	2 * 3	6
/	Division	3 / 2	1.5
\	Integer division	17 \ 5	3
Mod	Modulus	17 Mod 5	2
+	Addition	2 + 3	5
-	Subtraction	3 - 2	1
<<	Bit left shift	10110111 << 1	01101110
>>	Bit right shift	10110111 >> 1	01011011

The \ operator performs integer division. It returns the result of dividing its first operand by the second, dropping any remainder. It’s important to understand that the result is truncated toward zero, not rounded.

The Mod operator returns the remainder after dividing its first operand by its second. For example, 17 Mod 5 = 2 because 17 = 3 * 5 + 2.

The << operator shifts the bits of an integer value to the left, padding the empty bits on the right with zeros. For example, the byte value with bits 10110111 shifted 1 bit to the left gives 01101110. Shifting 10110111 2 bits to the left gives 11011100.

The >> operator shifts the bits of a value to the right, padding the empty bits on the left with zeros. For example, the byte value with bits 10110111 shifted 1 bit to the right gives 01011011. Shifting 10110111 2 bits to the right gives 00101101.

Unfortunately, Visual Basic doesn’t work easily with bit values, so you cannot use a binary value such as 10110111 in your code. Instead, you must write this value as the hexadecimal value &HB7 or the decimal value 183. The last two entries in the table show the values in binary, so it is easier to understand how the shifts work.

Tip 

The Calculator application that comes with Windows lets you easily convert between binary, octal, hexadecimal, and decimal. To start the Calculator, open the Start menu and Run. Type calc and click OK. Open the View menu and select Scientific. Now you can click the Bin, Oct, Dec, or Hex radio buttons to select a base, enter a value, and select another base to convert the value.