regex replacing at beginning of line in notepad++

Question

for example I have txt with content

qqqqaa
qqss
ss00

I want to replace only one q at the beginning of line, that is to get

qqqaa
qss
ss00

I tried replace ^q in notepad++. But After I click replaceAll, I got

aa
ss
ss00

What is wrong? Is my regex wrong? What is the correct form?

@WiktorStribiżew Nope, this is not what I want. I want to replace only one q, not replace two qs to one q — user15964
– user15964, Commented Jul 19, 2016 at 7:22
@WiktorStribiżew I just tried the same regex in Geany(another kind of editor) in which replace ^q works. So I thought it is a bug or a design of notepad++? — user15964
– user15964, Commented Jul 19, 2016 at 7:25
This is happening because Notepad++ does not replace them all at once, but one after the other. So after replacing first q (when there are more than one), then the next q is now at the beginning of the line. What I would do, replace ^q with space, then replace space in the beginning of the line with nothing. — Maria Ivanova
– Maria Ivanova, Commented Jul 19, 2016 at 7:26

Wiktor Stribiżew · Accepted Answer · 2016-07-19 07:27:34Z

4

The issue is that Notepad++ Replace All functionality replaces in a loop using the modified document.

The solution is to actually consume what we need to replace and keep within one regex expression like

^q(q*)

and replace with $1.

The pattern will find a q at the beginning of the line and then will capture into Group 1 zero or more occurrences of q after the first q, and in the replacement part the $1 will insert these qs inside Group 1 back into the string.

edited Jul 19, 2016 at 7:27

answered Jul 19, 2016 at 7:22

Wiktor Stribiżew

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2 Comments

user15964 Over a year ago

Thank you, Wiktor Stribiżew. regarding Notepad++ Replace All functionality replaces in a loop, I will open another post which maybe related.

Wiktor Stribiżew Over a year ago

You know, this is not the only funny thing with Notepad++ regex. E.g. \b\w is supposed to only match an alphanumeric or _ after a non-word char, but it will match all c, a and t in cat. I already opened a bug for that some months ago, no feedback :(

jansohn · Accepted Answer · 2016-07-19 07:33:03Z

1

You can use ^q(.+) and replace with $1 if you also want to replace single q's.

answered Jul 19, 2016 at 7:33

jansohn

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1 Comment

Wiktor Stribiżew Over a year ago

The same approach as described in my question, and a bit slower, but will work, yes.

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