5.5 Prevent a String from Including Dynamic Information

Problem

You want to prevent PowerShell from interpreting special characters or variable names inside a string.

Solution

Use a nonexpanding string to have PowerShell interpret your string exactly as entered. A nonexpanding string uses the single quote character around its text.

PS > $myString = 'Useful PowerShell characters include: $, `, " and { }'
PS > $myString
Useful PowerShell characters include: $, `, " and { }

If you want to include newline characters as well, use a nonexpanding here string, as in Example 5-1.

Example 5-1. A nonexpanding here string that includes newline characters

PS > $myString = @'
Tip of the Day
-------------
Useful PowerShell characters include: $, `, ', " and { }
'@

PS > $myString
Tip of the Day
Useful PowerShell characters include: $, `, ', " and { }

Discussion

In a literal string, all the text between the single quotes becomes part of your string. This is in contrast to an expanding string, where PowerShell expands variable names (such as $myString) and escape sequences (such as `n) with their values (such as the content of $myString and the newline character).

Note

Nonexpanding strings are a useful way to manage files and folders containing special characters that might otherwise be interpreted as escape sequences. For more information about managing files with special characters in their name, see Recipe 20.7.

As discussed in Recipe 5.1, one exception to the “all text in a literal string is literal” rule comes from the quote characters themselves. In either type of string, PowerShell lets you place two of that string’s quote characters together to include the quote character itself:

$myString = "This string includes ""double quotes"" because it combined quote
characters."
$myString = 'This string includes ''single quotes'' because it combined quote
characters.'