Named captures in PowerShell

Introduction

Named captures let you find parts of text and give each part a name. This makes it easy to get the exact piece you want without guessing positions.

You want to extract a date from a text and get the year, month, and day separately.

You need to find a person's name and phone number from a message and keep them labeled.

You want to check a log file and pull out error codes with their descriptions.

You are parsing a URL and want to get the protocol, domain, and path clearly.

You want to split a full name into first and last names from a string.

Syntax

PowerShell

'(?<name>pattern)'

Use inside parentheses to name a capture group.

You can access named groups by their name after matching.

Examples

Extract year, month, and day from a date string using named captures.

PowerShell

$text = 'Date: 2024-06-15'
if ($text -match '(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})') {
  $matches['year']
  $matches['month']
  $matches['day']
}

Capture first and last names separately from a full name.

PowerShell

$text = 'Name: John Doe'
if ($text -match 'Name: (?<first>\w+) (?<last>\w+)') {
  "$($matches['first']) $($matches['last'])"
}

Sample Program

This script finds the username and email from a string using named captures and prints them clearly.

PowerShell

$text = 'User: alice, Email: [e-mail]'
if ($text -match 'User: (?<username>\w+), Email: (?<email>\S+)') {
  Write-Output "Username: $($matches['username'])"
  Write-Output "Email: $($matches['email'])"
} else {
  Write-Output 'No match found.'
}

Important Notes

Named captures make your code easier to read and maintain.

The $matches automatic variable holds all named groups after a successful match.

If the pattern does not match, $matches will not contain the named groups.

Summary

Named captures label parts of a matched text for easy access.

Use the syntax (?<name>pattern) inside your regex.

Access captured parts by name using $matches['name'] in PowerShell.