Tutorials for handling text in PowerShell: replace, split, join, trim and compare strings, extract substrings, search with regular expressions and convert strings to other data types. See the main guide to PowerShell strings.
To convert a string to a script block in PowerShell, use [scriptblock]::Create(). Then run it with the call operator &: It’s useful when the code comes from a config file or is built from settings, like a filter. Below I cover parameters, the quoting trap, filters, syntax checks and the security risk you need to … Read more
To convert a hex string to a byte array in PowerShell 7, call [System.Convert]::FromHexString(). Windows PowerShell 5.1 doesn’t have that method, so there you convert each pair of hex digits with [Convert]::ToByte($pair, 16): Below I show both, then a function that handles spaces, dashes and 0x prefixes, checks the input, and turns the bytes back … Read more
To find invalid characters in a string in PowerShell, compare it against the characters Windows doesn’t allow. For file names, IndexOfAny with GetInvalidFileNameChars returns the position of the first bad one, or -1 if the name is clean: “Invalid” depends on where the text is going, though. Below I check file names, list every bad … Read more
To find a carriage return in a string in PowerShell, look for the escape sequence “`r”. Contains() tells you whether it’s there, and IndexOf() tells you where: Carriage returns are invisible, so they cause some of the most confusing bugs, like two strings that look the same but don’t match. Below I make them visible, … Read more
To replace a string before a character in PowerShell, use the -replace operator with a regex that matches from the start of the string up to that character: That pattern stops at the first colon. Below I’ll cover the last-occurrence version, keeping the delimiter, a no-regex option with IndexOf(), -split, special characters, file renames, and … Read more
The quickest PowerShell string starts with test is the StartsWith() method, which returns True or False: StartsWith() is case-sensitive, so I’ll also show the case-insensitive options, the -like and -match operators, and two traps where PowerShell 7 and Windows PowerShell 5.1 give different answers. Check if a string starts with text using StartsWith() The method … Read more
PowerShell throws “Cannot convert value to type System.String” when an advanced function’s [string] parameter receives an array instead of one value. Call it once per item, or join the items into one string: In this tutorial, I’ll show you how to reproduce cannot convert value to type system.string, find the hidden array behind it, and … Read more
To convert a string to a URI in PowerShell, cast it with the [uri] type accelerator. You get a System.Uri object with the scheme, host, path and query already split out: That works the same in PowerShell 7 and Windows PowerShell 5.1. The catch is in the details: the cast doesn’t really validate, and URL … Read more
To add a new line in a PowerShell string, put `n (backtick n) inside a double-quoted string. The text after it starts on the next line: Output: That covers most scripts. Below I show the other new line options, when each one matters, and how to turn spaces into new lines. I ran every example … Read more