How to remove part of a string with powershell?

Question

In powershell I have different strings with e.g. the following content (3 different examples):

name_something_else_10
another_name_200
what_ever_you_like_1234567

I want to cut of everything after the last underscore. So what I want to get is the following:

name_something_else
another_name
what_ever_you_like

Each string is provided as a variable, and I need the result in a variable as well. What I am then looking for is how to cut the part of the string by using a function like follows:

$newString = CutOffEveryAfterUnderscore $oldString

Answer 1

You could use a regular expression ('_[^_]*$') combined with the replacefunction:

function Remove-LastUnderscore
{
    [CmdletBinding()]
    Param
    (
        [Parameter(Mandatory=$true,Position=0)]
        [string]
        $string
    )

    $string -replace '_[^_]*$'
}

Now you can use it like:

$newString =  Remove-LastUnderscore $oldString

or without a function:

$newString =  $oldString -replace '_[^_]*$'

Note: This solution also works with strings without an underscore.

Answer 2

One way of doing it:

function Get-Prefix
{
    param($str)
    return $str.substring(0, $str.lastindexof('_'))
}

$strings = @("name_something_else_10",
    "another_name_200",
    "what_ever_you_like_1234567"
)

$strings | %{
    Get-Prefix $_
}