How do I pass multiple parameters into a function in PowerShell

Question

If I have a function which accepts more than one string parameter  the first parameter seems to get all the data assigned to it  and remaining parameters are passed in as empty   A quick test script   Function Test  string  arg1   string  arg2        Write-Host    arg1 value   arg1      Write-Host    arg2 value   arg2     Test  ABC    DEF     The output generated is    arg1 value  ABC DEF  arg2 value     The correct output should be    arg1 value  ABC  arg2 value  DEF   This seems to be consistent between v1 and v2 on multiple machines  so obviously  I m doing something wrong  Can anyone point out exactly what

User · Answer

If you don t know  or care  how many arguments you will be passing to the function  you could also use a very simple approach like   Code   function FunctionName         Write-Host  args     That would print out all arguments  For example   FunctionName a b c 1 2 3   Output  a b c 1 2 3   I find this particularly useful when creating functions that use external commands that could have many different  and optional  parameters  but relies on said command to provide feedback on syntax errors  etc   Here is a another real-world example  creating a function to the tracert command  which I hate having to remember the truncated name    Code   Function traceroute       Start-Process -FilePath   env systemroot system32 tracert exe  -ArgumentList  args -NoNewWindow

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I don t know what you re doing with the function  but have a look at using the  param  keyword  It s quite a bit more powerful for passing parameters into a function  and makes it more user friendly  Below is a link to an overly complex article from Microsoft about it  It isn t as complicated as the article makes it sound    Param Usage  Also  here is an example from a question on this site   Check it out

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Function Test       Param  string  arg1   string  arg2       Write-Host  arg1     Write-Host  arg2     This is a proper params declaration   See about Functions Advanced Parameters   And it indeed works

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The correct answer has already been provided  but this issue seems prevalent enough to warrant some additional details for those wanting to understand the subtleties   I would have added this just as a comment  but I wanted to include an illustration--I tore this off my quick reference chart on PowerShell functions  This assumes function f s signature is f  a   b   c      Thus  one can call a function with space-separated positional parameters or order-independent named parameters  The other pitfalls reveal that you need to be cognizant of commas  parentheses  and white space   For further reading  see my article Down the Rabbit Hole  A Study in PowerShell Pipelines  Functions  and Parameters  The article contains a link to the quick reference wall chart as well

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I don t see it mentioned here  but splatting your arguments is a useful alternative and becomes especially useful if you are building out the arguments to a command dynamically  as opposed to using Invoke-Expression   You can splat with arrays for positional arguments and hashtables for named arguments  Here are some examples  Splat With Arrays  Positional Arguments  Test-Connection with Positional Arguments Test-Connection www google com localhost  With Array Splatting  argumentArray    www google com    localhost  Test-Connection  argumentArray   Note that when splatting  we reference the splatted variable with an   instead of a    It is the same when using a Hashtable to splat as well   Splat With Hashtable  Named Arguments  Test-Connection with Named Arguments Test-Connection -ComputerName www google com -Source localhost  With Hashtable Splatting  argumentHash        ComputerName    www google com    Source    localhost    Test-Connection  argumentHash  Splat Positional and Named Arguments Simultaneously Test-Connection With Both Positional and Named Arguments Test-Connection www google com localhost -Count 1  Splatting Array and Hashtables Together  argumentHash        Count   1    argumentArray    www google com    localhost  Test-Connection  argumentHash  argumentArray

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Function Test  string  arg1   string  arg2        Write-Host    arg1 value   arg1      Write-Host    arg2 value   arg2     Test  ABC     DEF

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Because this is a frequent viewed question  I want to mention that a PowerShell function should use approved verbs  Verb-Noun as the function name   The verb part of the name identifies the action that the cmdlet performs  The noun part of the name identifies the entity on which the action is performed  This rule simplifies the usage of your cmdlets for advanced PowerShell users    Also  you can specify things like whether the parameter is mandatory and the position of the parameter   function Test-Script        CmdletBinding        Param                Parameter Mandatory  true  Position 0            string  arg1            Parameter Mandatory  true  Position 1            string  arg2            Write-Host    arg1 value   arg1      Write-Host    arg2 value   arg2        To pass the parameter to the function you can either use the position   Test-Script  Hello   World    Or you specify the parameter name   Test-Script -arg1  Hello  -arg2  World    You don t use parentheses like you do when you call a function within C      I would recommend to always pass the parameter names when using more than one parameter  since this is more readable

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Parameters in calls to functions in PowerShell  all versions  are space-separated  not comma separated  Also  the parentheses are entirely unneccessary and will cause a parse error in PowerShell 2 0  or later  if Set-StrictMode -Version 2 or higher is active  Parenthesised arguments are used in  NET methods only  function foo  a   b   c        quot a   a  b   b  c   c quot     ps gt  foo 1 2 3 a  1  b  2  c  3

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I stated the following earlier   The common problem is using the singular form  arg  which is incorrect  It should always be plural as  args   The problem is not that   In fact   arg can be anything else  The problem was the use of the comma and the parentheses     I run the following code that worked and the output follows   Code   Function Test  string  var1   string  var2        Write-Host    var1 value   var1      Write-Host    var2 value   var2      Test  ABC   DEF    Output    var1 value  ABC  var2 value  DEF

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Function Test  string  arg1   string  arg2        Write-Host    arg1 value   arg1      Write-Host    arg2 value   arg2     Test  ABC   DEF

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If you re a C    Java   C     Ruby   Python   Pick-A-Language-From-This-Century developer and you want to call your function with commas  because that s what you ve always done  then you need something like this    myModule   New-Module -ascustomobject        function test  arg1   arg2             echo  arg1    arg1  and arg2    arg2            Now call    myModule test  ABC    DEF     and you ll see  arg1   ABC  and arg2   DEF

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You can pass parameters in a function like this also   function FunctionName         Param   string  ParamName         Operations

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You call PowerShell functions without the parentheses and without using the comma as a separator  Try using   test  ABC   DEF    In PowerShell the comma     is an array operator  e g    a    one    two    three    It sets  a to an array with three values

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There are some good answers here  but I wanted to point out a couple of other things  Function parameters are actually a place where PowerShell shines  For example  you can have either named or positional parameters in advanced functions like so   function Get-Something       Param                 Parameter Mandatory  true  Position 0             string   Name            Parameter Mandatory  true  Position 1             int   Id           Then you could either call it by specifying the parameter name  or you could just use positional parameters  since you explicitly defined them  So either of these would work   Get-Something -Id 34 -Name  Blah  Get-Something  Blah  34   The first example works even though Name is provided second  because we explicitly used the parameter name  The second example works based on position though  so Name would need to be first  When possible  I always try to define positions so both options are available   PowerShell also has the ability to define parameter sets  It uses this in place of method overloading  and again is quite useful   function Get-Something        CmdletBinding DefaultParameterSetName  Name        Param                 Parameter Mandatory  true  Position 0  ParameterSetName  Name              string   Name            Parameter Mandatory  true  Position 0  ParameterSetName  Id              int   Id           Now the function will either take a name  or an id  but not both   You can use them positionally  or by name  Since they are a different type  PowerShell will figure it out  So all of these would work   Get-Something  some name  Get-Something 23 Get-Something -Name  some name  Get-Something -Id 23   You can also assign additional parameters to the various parameter sets   That was a pretty basic example obviously   Inside of the function  you can determine which parameter set was used with the  PsCmdlet ParameterSetName property  For example   if  PsCmdlet ParameterSetName -eq  Name         Write-Host  Doing something with name here      Then  on a related side note  there is also parameter validation in PowerShell  This is one of my favorite PowerShell features  and it makes the code inside your functions very clean  There are numerous validations you can use  A couple of examples are   function Get-Something       Param                 Parameter Mandatory  true  Position 0             ValidatePattern   Some                string   Name            Parameter Mandatory  true  Position 1             ValidateRange 10 100             int   Id           In the first example  ValidatePattern accepts a regular expression that assures the supplied parameter matches what you re expecting   If it doesn t  an intuitive exception is thrown  telling you exactly what is wrong  So in that example   Something  would work fine  but  Summer  wouldn t pass validation   ValidateRange ensures that the parameter value is in between the range you expect for an integer  So 10 or 99 would work  but 101 would throw an exception   Another useful one is ValidateSet  which allows you to explicitly define an array of acceptable values  If something else is entered  an exception will be thrown  There are others as well  but probably the most useful one is ValidateScript  This takes a script block that must evaluate to  true  so the sky is the limit  For example   function Get-Something       Param                 Parameter Mandatory  true  Position 0             ValidateScript   Test-Path    -PathType  Leaf                ValidateScript    Get-Item      select -Expand Extension  -eq   csv                string   Path           In this example  we are assured not only that  Path exists  but that it is a file   as opposed to a directory  and has a  csv extension      refers to the parameter  when inside your scriptblock   You can also pass in much larger  multi-line script blocks if that level is required  or use multiple scriptblocks like I did here  It s extremely useful and makes for nice clean functions and intuitive exceptions

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If you try   PS  gt  Test  ABC    GHI     DEF     you get     arg1 value  ABC GHI  arg2 value  DEF   So you see that the parentheses separates the parameters    If you try   PS  gt   var    C  PS  gt  Test   AB     var   DEF    you get    arg1 value  ABC  arg2 value  DEF   Now you could find some immediate usefulness of the parentheses - a space will not become a separator for the next parameter - instead you have an eval function

[powershell] How do I pass multiple parameters into a function in PowerShell?

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