regex - Powershell select-string returns different values depending on number of matches -

i have report file generated , containes various file references. using select-string , regular expressions match on types of files , perform subsequent processing on them.

the dilemma have trying consistently identify number of matches when there 0 (0), 1 (1), or more 1 (2+) matches. here i've tried:

(select-string -path $outputfilepath -pattern $regex -allmatches).matches.count 

this return "null" if there 0 matches, "1" if 1 match, , "null" if more 1 match.

(select-string -path $outputfilepath -pattern $regex -allmatches).count 

this return "null" if there 0 or 1 match , number of matches if more 1 match.

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i'm faily new powershell, trying find consistent way test on number of matches regardless of whether there 0, 1, or more 1 match.

try this:

$content = get-content $outputfilepath ($content -match $regex).count 

powershell has number of comparison operators make life easier. here's quick listing:

-eq -ne -gt -ge    -lt -le -like -notlike -match -notmatch -contains -notcontains -in -notin -replace 

in instance, -match match $content string against regular expression $regex, , output grouped parenthesis. grouping collection of strings. can count objects , print out accurate count of matches.

so why doesn't code work expected? when have single match, .matches returns system.text.regularexpressions.match object looks string "test123":

groups   : {test123} success  : true captures : {test123} index    : 15 length   : 7 value    : test123 

why happen? because microsoft.powershell.commands.matchinfo object select-string returns. can verify attempting other properties .filename on single-match output.

okay, why can't of our matches in 1 go? because multiple matches return multiple objects, have collection you're trying operate on. collection has different type, , doesn't understand .matches. no collection returned on 1 match, instead single object understand .matches is!

long story short: these aren't outputs you're looking for!