Strings, Formatting and Regex

By the end of this lesson you'll format text precisely with the -f operator and here-strings, slice and stitch strings with methods, -split, and -join, and wield regular expressions through -replace, -match/$Matches, and Select-String — the toolkit for parsing logs, reshaping data, and validating input.

Learn Strings, Formatting and Regex in our free PowerShell course — an interactive lesson with worked examples, a practice exercise and a quick reference.

Part of the free Powershell course at LearnCodingFast — hands-on lessons with examples you run in your browser, plus practice exercises and a quick quiz.

Working with text is like being a tailor . The -f operator is your tape measure and pattern — it lays values into exact, aligned slots. -split and -join are scissors and needle : cut a string into pieces, then stitch them back the way you want. And regex is your master pattern — a reusable template that recognises a shape (a date, an email, a log level) anywhere it appears, so you can find it, extract it, or reshape it with surgical precision.

1. Formatting with -f & Here-Strings

The -f operator fills numbered placeholders ( {' '} , {' '} , …) with values and supports .NET format specifiers after a colon — {' '} for two decimals, {' '} for a percentage, {' '} for alignment. A here-string ( ) holds multiple lines verbatim and still expands $variables , which is perfect for templates and reports. Read this worked example, then run it.

2. String Methods, -split & -join

Because strings are .NET objects, they carry methods like .Trim() , .ToUpper() , .Replace() , and .Substring() . To break a string apart, use the -split operator (its delimiter is a regex); to glue an array back together, use -join . These two are the bread and butter of turning raw text into structured data and back.

Now you try. Fill in the two blanks using the hints in the comments, then run it.

3. Regular Expressions: -match , $Matches & -replace

The -match operator tests a string against a regex and, on success, fills the automatic $Matches hashtable: $Matches[0] is the whole match, numbered/named groups follow. -notmatch is its inverse. The -replace operator edits text using regex and back-references ( $1 , $2 ) in the replacement. Remember these operators are case-insensitive by default — prefix with c ( -cmatch ) for case sensitivity.

PowerShell's escape character is the backtick , not the backslash. Inside double quotes, n is a newline. But in a regex pattern, the backslash still has its normal regex meaning ( \d , \. ) — so write regex patterns in single quotes to stop PowerShell touching the backslashes.

Select-String is PowerShell's grep : it searches piped text or files on disk for a regex and returns rich match objects (with file name and line number). Add -SimpleMatch for a literal, non-regex search.

Each result is a MatchInfo object, so you can pipe it onward — e.g. Select-String 'ERROR' app.log | Select-Object LineNumber, Line .

No blanks this time — just a brief and an outline to keep you on track. Build it, run it, and check your output against the example in the comments. Pulling structured fields out of raw log text is one of the most common real-world scripting jobs.

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