Get-EvenNumber.ps1

1. # Requires –Version:2.0 
2. # Get-EvenNumber.ps1 
3. # Gets an even number 
4. # Demonstrates Version 2 functionality 
5. # Updates Andget-=y Schneider's example at 
6. # http://get-powershell.com/2008/12/23/industrial-strength-functions-in-powershell-v2-ctp-3/ 
7.  
8. function Get-EvenNumber { 
9. #.Synopsis 
10. #    Detects and reports on even numbers using the Modulo operator (%) 
11. #.Description 
12. #    Takes a pipeline of values and tells you the numbers that are are even  
13. #    integers. PowerShell detects non-integers.  At the end, this function 
14. #    tells you how many numbers were processed and how many were even. Non-Inteers 
15. #    are not reported. 
16. #.Parameter number 
17. #    One or more integers - values can come from the pipeline as well    
18. #.Example 
19. #    1..10 | Get-EvenNumber 
20. #.Example 
21. #    1,2,3,4,"foo" | get-EvenNumber
22. #    (Generates an error) 
23.  
24. param ( 
25. [Parameter(Position=0,  
26. Mandatory=$true,  
27. ValueFromPipeline=$true,  
28. HelpMessage="Please type a integer")] 
29. [Alias("integer")] [int32] 
30.  $number 
31. ) 
32. # Begin block - just type out a greeting and initialise 
33. begin {"Beginning of Pipeline";  
34.        $i=$j=0 
35. } 
36.  
37. process { 
38.  $i++  
39.  if (($number % 2) -eq 0) {"$number is even"; $j++} 
40. } 
41.  
42. end { 
43. "End of Pipeline";  
44. "{0} integers processed" -f $i;  
45. "{0} were even" -f $j 
46. } 
47. } 

This script produces the following output:

PS C:\foo> 1..10 | Get-EvenNumber
Beginning of Pipeline
2 is even
4 is even
6 is even
8 is even
10 is even
End of Pipeline
10 integers processed
5 were even

PS C:\foo> -22,200000,2 | Get-EvenNumber
Beginning of Pipeline
-22 is even
200000 is even
2 is even
End of Pipeline
3 integers processed
3 were even

PS C:\foo> "foo" | Get-EvenNumber
Begining of Pipeline
Get-EvenNumber : Cannot process argument transformation on parameter 'number'. Cannot convert value "foo" to type "System.Int32". Error:
"Input string was not in a correct format."
At line:1 char:23
+ "foo" | Get-EvenNumber <<<<
    + CategoryInfo          : InvalidData: (foo:String) [Get-EvenNumber], ParameterBindin...mationException
    + FullyQualifiedErrorId : ParameterArgumentTransformationError,Get-EvenNumber

End of Pipeline
0 integers processed
0 were even

PS C:\foo> 123456789012 | Get-EvenNumber
Begining of Pipeline
Get-EvenNumber : Cannot process argument transformation on parameter 'number'. Cannot convert value "123456789012" to type "System.Int32"
. Error: "Value was either too large or too small for an Int32."
At line:1 char:30
+ 123456789012 | Get-EvenNumber <<<<
    + CategoryInfo          : InvalidData: (123456789012:Int64) [Get-EvenNumber], ParameterBindin...mationException
    + FullyQualifiedErrorId : ParameterArgumentTransformationError,Get-EvenNumber

End of Pipeline
0 integers processed
0 were even

PS C:\foo> Get-Help Get-EvenNumber -Full

NAME
    Get-EvenNumber

SYNOPSIS
    Detects and reports on even numbers using the Modulo operator (%)

SYNTAX
    Get-EvenNumber [-number] [<Int32>] [-Verbose] [-Debug] [-ErrorAction [<ActionPreference>]] [-WarningAction [<ActionPreference>]] [-Er
    rorVariable [<String>]] [-WarningVariable [<String>]] [-OutVariable [<String>]] [-OutBuffer [<Int32>]] [<CommonParameters>]

DETAILED DESCRIPTION
    Takes a pipeline of values and tells you the numbers that are are even
    integers. PowerShell detects non-integers.  At the end, this function
    tells you how many numbers were processed and how many were even. Non-Inteers
    are not reported.

PARAMETERS
    -number
        One or more integers - values can come from the pipeline as well

        Required?                    true
        Position?                    0
        Default value
        Accept pipeline input?       true (ByValue)
        Accept wildcard characters?

    <CommonParameters>
        This cmdlet supports the common parameters: -Verbose, -Debug,
        -ErrorAction, -ErrorVariable, -WarningAction, -WarningVariable,
        -OutBuffer and -OutVariable. For more information, type,
        "get-help about_commonparameters".

INPUT TYPE

RETURN TYPE

    -------------------------- EXAMPLE 1 --------------------------

    1..10 | Get-EvenNumber

    -------------------------- EXAMPLE 2 --------------------------

    1,2,3,4,"foo" | get-EvenNumber
    (Generates an error)

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