Koans/Introduction/AboutNumbers.Koans.ps1
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using module PSKoans [Koan(Position = 103)] param() <# Numbers In PowerShell, we can use many different data types to represent numbers. All differ slightly in what they can and can't do. The two most common ones are: Integers Represent whole numbers. This is the default numeric data type that PowerShell uses for whole numbers Doubles Represents numbers with decimal places or exponent. This is the default numeric type that PowerShell will use for numbers entered with decimal places or exponents, for example: 0.5 or 2e3 So 10 will be an integer and 10.0 will be a double. The examples below display some of the differences inherent to the numeric types. #> Describe 'Basic Number Types' { Context 'Double' { It 'can result from an operation involving multiple types of numbers' { $Int = 10 $Double = 10.0 'System.____' | Should -Be $Int.GetType().Fullname 'System.____' | Should -Be $Double.GetType().Fullname $Result = $Int * $Double # What type results when you multiply integers and doubles? 'System.____' | Should -Be $Result.GetType().Fullname } } Context 'Integers' { It 'has to be a whole number' { function Get-Number { param( [Parameter(Mandatory)] [int] $Number ) $Number } $Pi = [Math]::PI 'System.____' | Should -be $Pi.GetType().Fullname # What number will return if you pass Pi into an int function? ___ | Should -Be (Get-Number -Number $Pi) } } } Describe "Banker's Rounding" { It 'rounds to nearest even number on .5' { <# The rounding used in PowerShell is called "Rounding to Even" or "Banker's Rounding". Numbers will be rounded to the nearest _even_ Integer. This behaviour stems from the underlying library method [math]::Round() which is documented in more detail here: https://docs.microsoft.com/en-us/dotnet/api/system.math.round#midpoint-values-and-rounding-conventions #> # Try and guess how PowerShell will round these numbers ____ | Should -Be ([int]2.5) ____ | Should -Be ([int]3.34) ____ | Should -Be ([int]10.61) ____ | Should -Be ([int]12.7) ____ | Should -Be ([int]5.5) } } |