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regexpowershellcase-insensitive
mishkin
mishkin

Reputation: 6242

Pass regex options to PowerShell [regex] type

I capture two groups matched using the regexp code below:

[regex]$regex = "^([0-9]{1,20})(b|kb|mb|gb|tb)$"

$matches = $regex.match($minSize)

$size=[int64]$matches.Groups[1].Value
$unit=$matches.Groups[2].Value

My problem is I want to make it case-insensitive, and I do not want to use regex modifiers.

I know you can pass regex options in .NET, but I cannot figure out how to do the same with PowerShell.

Upvotes: 12

Views: 17600

Answers (5)

jrobiii
jrobiii

Reputation: 141

You can also include mode modifier like (?i) in your regex, like so (cmatch forces case sensitive match):

PS H:\> 'THISISSOMETHING' -cmatch 'something'
False
PS H:\> 'THISISSOMETHING' -cmatch '(?i)something'
True

Upvotes: 6

AdamL
AdamL

Reputation: 13181

After using [regex] type accelerator, Options property is ReadOnly and can't be changed. But you can call a constructor with RegexOptions parameter: 

$regex = [System.Text.RegularExpressions.Regex]::new('^([0-9]{1,20})(b|kb|mb|gb|tb)$','IgnoreCase')

To pass multiple options use bitwise or operator on underlying values:

$regex = [regex]::new('^([0-9]{1,20})(b|kb|mb|gb|tb)$',[System.Text.RegularExpressions.RegexOptions]::Multiline.value__ -bor [System.Text.RegularExpressions.RegexOptions]::IgnoreCase.value__)

But simple addition seems to work, too:

[System.Text.RegularExpressions.RegexOptions]::Multiline + System.Text.RegularExpressions.RegexOptions]::IgnoreCase

It would even work when supplied numeric flag (35 = IgnoreCase=1 + MultiLine=2 + IgnorePatternWhitespace=32), altough relying on enum values directly is usually not a best practice:

$regex = [regex]::new('^([0-9]{1,20})(b|kb|mb|gb|tb)$',36)
$regex.Options

Upvotes: 2

argonym
argonym

Reputation: 892

There are overloads of the static [Regex]::Match() method that allow to provide the desired [RegexOptions] programmatically:

# You can combine several options by doing a bitwise or:
$options = [Text.RegularExpressions.RegexOptions]::IgnoreCase -bor [Text.RegularExpressions.RegexOptions]::CultureInvariant
# or by letting casting do the magic:
$options = [Text.RegularExpressions.RegexOptions]'IgnoreCase, CultureInvariant'

$match = [regex]::Match($input, $regex, $options)

Upvotes: 19

Shay Levy
Shay Levy

Reputation: 126902

Use PowerShell's -match operator instead. By default it is case-insensitive:

$minSize -match '^([0-9]{1,20})(b|kb|mb|gb|tb)$'

For case-sensitive matches, use -cmatch.

Upvotes: 11

aquinas
aquinas

Reputation: 23796

Try using -match instead. E.g.,

$minSize = "20Gb"
$regex = "^([0-9]{1,20})(b|kb|mb|gb|tb)$"
$minSize -match $regex #Automatic $Matches variable created
$size=[int64]$Matches[1]
$unit=$Matches[2]

Upvotes: 8

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