Mod: Modulo Division ExampleUse the Mod operator to perform modulo division. Use Mod in a loop construct.
VB.NET
Mod. How can you use modulo division in the VB.NET language? With the Mod operator, you can compute the remainder of a division expression. Mod is equivalent to the modulo operator in C-like languages. With Mod we can determine whether a number is odd or even (its parity).
Example. This example shows some Mod expressions with constant Integers. When the value 90 goes into 1000 11 times, but leaves a remainder of 10. This is the result of 1000 Mod 90.
And The next Mod expressions show the same principle in action. The Console output is shown.
Console Module Module1 Sub Main() ' Compute some modulo expressions with Mod. Console.WriteLine(5 Mod 3) Console.WriteLine(1000 Mod 90) Console.WriteLine(100 Mod 90) Console.WriteLine(81 Mod 80) Console.WriteLine(1 Mod 1) End Sub End Module
2 10 10 1 0
Loop example. Using a Mod expression is appropriate in a For-loop. You can apply Mod to the variable "i". In this program, we display "i" whenever it is divisible by 10.
For Each, For
If Then
Detail This style of code is useful in real programs. We can "throttle" an action to occur only occasionally this way.
Module Module1 Sub Main() ' Loop through integers. For i As Integer = 0 To 200 - 1 ' Test i with Mod 10. If i Mod 10 = 0 Then Console.WriteLine(i) End If Next End Sub End Module
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190
Odd, even numbers. The parity of a number is whether it is odd or even. We can test parity by creating 2 functions in VB.NET that return true or false.
Detail This returns the opposite of IsEven. It correctly handles negative and positive numbers.
Detail This uses modulo division (with Mod) to see if the number is evenly divisible by 2 (and thus even).
Detail Both methods return a Boolean (true or false). We test these methods with a simple For-loop.
Boolean
Module Module1 Function IsOdd(ByVal number As Integer) As Boolean ' Handle negative numbers by returning the opposite of IsEven. Return IsEven(number) = False End Function Function IsEven(ByVal number As Integer) As Boolean ' Handles all numbers because it tests for 0 remainder. ' ... This works for negative and positive numbers. Return number Mod 2 = 0 End Function Sub Main() For i = -10 To 10 Console.WriteLine(i.ToString() + " EVEN = " + IsEven(i).ToString()) Console.WriteLine(i.ToString() + " ODD = " + IsOdd(i).ToString()) Next End Sub End Module
-10 EVEN = True -10 ODD = False -9 EVEN = False -9 ODD = True -8 EVEN = True -8 ODD = False -7 EVEN = False -7 ODD = True -6 EVEN = True -6 ODD = False -5 EVEN = False -5 ODD = True -4 EVEN = True -4 ODD = False -3 EVEN = False -3 ODD = True -2 EVEN = True -2 ODD = False -1 EVEN = False -1 ODD = True 0 EVEN = True 0 ODD = False 1 EVEN = False 1 ODD = True 2 EVEN = True 2 ODD = False 3 EVEN = False 3 ODD = True 4 EVEN = True 4 ODD = False 5 EVEN = False 5 ODD = True 6 EVEN = True 6 ODD = False 7 EVEN = False 7 ODD = True 8 EVEN = True 8 ODD = False 9 EVEN = False 9 ODD = True 10 EVEN = True 10 ODD = False
Syntax note. In C-like languages, the "%" character expresses a modulo division. We cannot use this character in VB.NET. Instead the Mod operator is used.
A summary. Modulo division is an important concept to understand in computer programming. In .NET, modulo division is used to implement collections such as Dictionary.
Dictionary
The Mod operator often comes in handy whenever a mathematical procedure is needed. We can use modulo for determining parity (odd or even).
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Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.