Can I remove a substring from a string starting at a known position and ending at a given character?

Question

I need to extract sections of a string but I won't always know the length/content.

I've tried converting the string to XML or JSON for instance, and can't come up with any other way to achieve what I'm looking for.

Example string:

'Other parts of the string Name="SomeRandomAmountOfCharacters" blah blah'

What I need to remove always starts with an attribute name and ends with a closing double quote. So can I say I'd like to remove substring starting at Name=" and go until we reach the closing "?

Expected result:

'Other parts of the string blah blah'

Ansgar Wiechers · Accepted Answer · 2019-01-08T00:11:32.373

1

You'll want to do something like this

$s = 'Other parts of the string Name="SomeRandomAmountOfCharacters" blah blah'
$s -replace ' Name=".*?"'

or like this:

$s = 'Other parts of the string Name="SomeRandomAmountOfCharacters" blah blah'
$s -replace ' Name="[^"]*"'

to avoid unintentionally removing other parts of your string in case it contains multiple attributes or additional double quotes. .*? is a non-greedy match for a sequence of any character except newlines, so it'll match up to the next double quote. [^"]* is a character class matching the longest consecutive sequence of characters that aren't double-quotes, so it'll also match up to the next double quote.

You'll also want to add the miscellaneous construct (?ms) to your expression if you have a multiline string.

edited Jan 08 '19 at 00:11

answered Jan 07 '19 at 23:18

Ansgar Wiechers

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This is exactly what I need. The other answers were great, but you accounted for the possibility of additional attributes. – user2524237 Jan 07 '19 at 23:27
I've never seen the pattern `.*?` before. What role does the question mark after the asterisk play? – Andrew Shepherd Jan 07 '19 at 23:32
Never mind, I found the explanation: https://stackoverflow.com/questions/3075130/what-is-the-difference-between-and-regular-expressions – Andrew Shepherd Jan 07 '19 at 23:33

score 0 · Answer 2 · answered Jan 07 '19 at 22:47

0

Here is a good reference: https://www.regular-expressions.info/powershell.html

In your case

$s = 'Other parts of the string Name="SomeRandomAmountOfCharacters" blah blah'
$s -replace '\W*Name=".*"\W*', " "

or

$newString = $s -replace 'W*Name=".*"\W*', " "

This will replace your matching string, including the surrounding whitespace, with a single space.

answered Jan 07 '19 at 22:47

Andrew Shepherd

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This is a great answer, thank you. Brought me very close to what I needed. – user2524237 Jan 07 '19 at 23:28

score 0 · Answer 3 · answered Jan 07 '19 at 22:49

Look at something like this and understand how it works.

$pattern = '(.*)Name=".*" (.*)'
$str = 'Other parts of the string Name="SomeRandomAmountOfCharacters" blah blah'

$ret = $str -match $pattern

$out = $Matches[1]+$Matches[2]

$str
"===>"
$out

See also: https://regex101.com/r/wM2xlc/1

Can I remove a substring from a string starting at a known position and ending at a given character?

3 Answers3