Splitting a string and selecting a substring in PowerShell - powershell

Question

I am attempting to isolate and return a small variable string from a larger string.
I am struggling because the larger string I am extracting from is in list format. I can split this into substrings successfully, but I do not know how to select one of these substrings without returning the entire string. The string is generated by a command line process.
$StringList
AppTitle1.1.1221.aaa111
AppSubTitle
AnotherAppTitle1.1.1221.aaa111
AnotherAppSubTitle
...and so on
I can split the list string into substrings by line using regular expressions to split at whitespace (there is no whitespace within any given line).
$StringList -split "\s"
Once I have split the string into the desired substrings, however, I am not sure how to select the desired substring. The length of the list (i.e. the number of apps present in it) and the location of the app I need to retrieve the title of within that list are entirely variable, so I cannot simply use substring reference numbers. I've tried several approaches to selecting the substring, but each has simply returned the entire string, or nothing at all.
Here are two approaches I've attempted. The first returns the entire string list and the second returns nothing.
$DesiredAppTitle = Select-String -InputObject $StringList -Pattern "AnotherAppTitle"
or
$DesiredAppTitle = foreach ($_.substring in $StringList)
{
if ($_.substring -contains "AnotherAppTitle")
{
return $_.name
}
}
What I'd like for it to return is:
AnotherAppTitle1.1.1221.aaa111
I'm sure there are a million ways to do this, so if neither of my approaches seems like a good fit, I'm open to other suggestions. Any assistance would be greatly appreciated. Thanks in advance!

Answer 1

# Multi-line input string.
$StringList = #'
AppTitle1.1.1221.aaa111
AppSubTitle
AnotherAppTitle1.1.1221.aaa111
AnotherAppSubTitle
'#
# Split it into whitespace-separated tokens.
$tokens = -split $StringList
# Match the token of interest.
$tokens -match '^AnotherAppTitle'
The above yields:
AnotherAppTitle1.1.1221.aaa111
Note the use of regex-matching operator with anchor ^ to ensure that the search term matches at the start of a token, and the use of the unary form of the -split operator, which splits the input by any nonempty whitespace runs.
As for what you tried:
If you pass a multi-line string to Select-String, it is considered a single "line" and, in case of a match, that whole "line" is output.
foreach ($_.substring in $StringList) won't even run, because $_.substring is not a valid iteration variable (you shouldn't use $_, which is an automatic variable, as an enumeration variable at all, and the .substring access breaks the syntax).
If you used $_ instead of $_.substring, the loop would technically work (even though, again, $_ shouldn't be used as an iteration variable), but the loop would only execute once, for the entire multi-line string.
Even if $_.substring did refer to a line (it doesn't), -contains is the wrong operator to use, because it tests if a LHS collection contains the RHS value in full.
Also, use break to exit a loop, not return.
Using the -match approach as demonstrated at the top is the better approach, but if you did want to solve this with a foreach loop:
$DesiredAppTitle = foreach ($token in -split $StringList) {
if ($token -match '^AnotherAppTitle') { $token; break }
}