PowerShell and the -contains operator

Question

Consider the following snippet    12-18  -Contains  -    You   d think this evaluates to true  but it doesn t  This will evaluate to false instead  I   m not sure why this happens  but it does   To avoid this  you can use this instead    12-18  Contains  -     Now the expression will evaluate to true   Why does the first code snippet behave like that  is there something special about - that doesn t play nicely with -Contains  The documentation doesn t mention anything about it

User · Answer

You can use like    12-18  -like   -     Or split for contains    12-18  -split    -contains  -

User · Answer

-Contains is actually a collection operator  It is true if the collection contains the object  It is not limited to strings   -match and -imatch are regular expression string matchers  and set automatic variables to use with captures   -like  -ilike are SQL-like matchers

User · Answer

like is best  or at least easiest  match is used for regex comparisons    Reference  https   docs microsoft com en-us powershell module microsoft powershell core about about comparison operators view powershell-6

User · Answer

The -Contains operator doesn t do substring comparisons and the match must be on a complete string and is used to search collections   From the documentation you linked to      -Contains   Description  Containment operator  Tells whether a collection of reference values includes a single test value    In the example you provided you re working with a collection containing just one string item   If you read the documentation you linked to you ll see an example that demonstrates this behaviour   Examples   PS C   gt   abc    def  -Contains  def  True  PS C   gt   Windows    PowerShell  -Contains  Shell  False   Not an exact match   I think what you want is the -Match operator    12-18  -Match  -    Which returns True   Important  As pointed out in the comments and in the linked documentation  it should be noted that the -Match operator uses regular expressions to perform text matching

[powershell] PowerShell and the -contains operator

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