How to get sub string from a string

I am trying to get sub string from a string with powershell

$completeString = “C:\Development\Work\ABC-SharePoint\ABC\css\ABC\XYZ”

$startingString = “ABC”

I want “ABC\css\ABC\XYZ”

note: ABC is multiple times in string

That’s kind of tricky to answer with the limited information available. You have the string “ABC” here in “ABC-Sharepoint”, but you were interested in that part in the output. Are you looking for the first instance of "\ABC" and then everything else in the string? Or everything after "C:\Development\Work\ABC-SharePoint"? Something else entirely?

Here’s one example that gives you everything after (and including) the first instance of a folder named exactly ABC (not case sensitive).

$completeString = "C:\Development\Work\ABC-SharePoint\ABC\css\ABC\XYZ"
$startingString = "ABC"

$pattern = "^.*?\\(?=$([regex]::Escape($startingString))\\)"

$completeString -replace $pattern

This particular example uses a regular expression, which is a very powerful technique that is also a pain in the butt to read. Another alternative would be to split the string on the backslashes (or use the Split-Path cmdlet) and loop over the resulting array yourself to find the first instance of “ABC”, then join the rest of the array together. That code might look like this:

$completeString = "C:\Development\Work\ABC-SharePoint\ABC\css\ABC\XYZ"
$startingString = "ABC"

$array = $completeString -split '\\'

for ($i = 0; $i -lt $array.Count; $i++)
{
    if ($array[$i] -eq $startingString) { break }
}

$array[$i..($array.Count - 1)] -join '\'

I don’t know what happened to your code there when you pasted, Dave, but I think the last line should be

$array[$i..($array.Count)] -join '\'