Powershell is removing comma from program argument

I want to pass in a comma separated list of values into a script as part of a single switch.

Here is the program.

param(
[string]$foo
)

Write-Host "[$foo]"

Here is the usage example

PS> .\inputTest.ps1 -foo one,two,three

I would expect the output of this program to be `[one,two,three]` but instead it is returning `[one two three]`. This is a problem because I want to use the commas to deliminate the values.

Why is powershell removing the commas, and what do I need to change in order to preserve them?

The comma is a special symbol in powershell to denote an array separator.

Just put the arguments in quotes:

inputTest.ps1 -foo "one, two, three"

Alternatively you can 'quote' the comma:

inputTest.ps1 -foo one`,two`,three

Enclose it in quotes so it interprets it as one variable, not a comma-separated list of three:

>PS> .\inputTest.ps1 -foo "one,two,three"

Following choices are available

1. Quotes around all arguments (')

<code>inputTest.ps1 -foo 'one,two,three'</code>

2. Powershell's escape character before each comma (grave-accent (`))

<code>inputTest.ps1 -foo one`,two`,three</code>

**Double quotes** around arguments don't change anything !
**Single quotes** eliminate expanding.
**Escape character** (grave-accent) eliminates expanding of next character

if you are passing parameters from a batch file, then enclse your params as below
"""Param1,Param2,Param3,Param4"""

Powershell will remove the commas and use them to delimitate an array. You can join the array elements back into a string and put a comma between each one.

param(
[string[]]$foo
)
$foo_joined = $foo -join ","
write-host "[$foo_joined]"

Any spaces between your arguments will be removed, so this:

`PS> .\inputTest.ps1 -foo one, two, three`

will also output: `[one,two,three]`

If you need the spaces you'll need quotes, so do this:

`PS> .\inputTest.ps1 -foo one,"two is a pair"," three"`

if you want to output: `[one,two is a pair, three]`