The -match and -notmatch operators return true or false when testing strings:

'The cow jumped over the moon' -match 'cow'  # Returns true 
'The       cow' -match 'The +cow'            # Returns true 

In the preceding example, the + symbol is reserved; it indicates that The is followed by one or more spaces before cow.

In addition to returning a true or false value about the state of the match, a successful match will add values to a reserved variable, $matches. For example, the following regular expression uses a character class to indicate that it should match any character from 0 to 4, repeated 0 or more times:

'1234567689' -match '[0-4]*' 

Once the match has been executed, the matches variable (a hashtable) will be populated with the part of the string that matched the expression:

PS> $matches

Name                                Value 
----                                ----- 
0                                   1234 

Regular expressions use parentheses to denote groups. Groups may be used to capture interesting elements of a string:

PS> 'Group one, Group two' -match 'Group (.*), Group (.*)'
True

PS> $matches

Name                        Value
----                        ----- 
2                           two 
1                           one 
0                           Group one, Group two 

In the preceding example, the match operator is run first, then the matches variable is displayed. The captured value one is held in the first group, and is accessible using either of the following statements:

$matches[1] 
$matches.1 

Matches is a hashtable, in the example above 1 is being used as a key to access the capture group.