Check that a string exists within another string with regular expression

Question

I've got a regular expression that I am using to strip an extension from another string

The extensions in this example are

BK|BZ|113

If the string does not contain any of the extensions, then I need it to leave the string as is.

The regular expression I'm using is

base_value = base_string[/(.*?[^-])-?(?:BK|BZ|113)/,1]

However, if the base_value does not contain the string, I want to return the base_value. I thought I could use

base_value = base_string
base_value = base_string[/(.*?[^-])-?(?:BK|BZ|113)/,1] unless (base_value !~ /(.*?[^-])-?(?:BK|BZ|113)) == false

but that isn't working.

What is the best way to return the base_string if the extensions are not found?

Can you give some example inputs?

Mark Byers
– Mark Byers

2011-09-28 22:52:48 +00:00
Commented Sep 28, 2011 at 22:52 — Mark Byers
– Mark Byers, Commented Sep 28, 2011 at 22:52

Guilherme Bernal · Accepted Answer · 2011-09-28 23:06:24Z

2

If I understand well, you want to strip the regexp from a string, if it matches, right? So.. do it:

string.sub(/(?:BK|BZ|113)$/, "")

answered Sep 28, 2011 at 23:06

Guilherme Bernal

8,32329 silver badges44 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

derp Over a year ago

Your approach is the better than mine, I guess I got stuck on what he had written, up!

derp · Accepted Answer · 2011-09-28 23:07:08Z

0

Perhaps you can use sub like this:

base_string1 = "test1BK"
base_string2 = "test2"

p base_string1.sub(/(.*?[^-])-?(?:BK|BZ|113)/,'\1')
p base_string2.sub(/(.*?[^-])-?(?:BK|BZ|113)/,'\1')

When the pattern is not found nothing is replaced, otherwise it returns the string without the extension.

answered Sep 28, 2011 at 23:07

derp

3,07020 silver badges16 bronze badges

Comments

mu is too short · Accepted Answer · 2011-09-28 23:10:35Z

0

If /(.*?[^-])-?(?:BK|BZ|113)/ doesn't match then base_string[/(.*?[^-])-?(?:BK|BZ|113)/,1] will be nil. So this should work:

base_value = base_string[/(.*?[^-])-?(?:BK|BZ|113)/,1] || base_string

answered Sep 28, 2011 at 23:10

mu is too short

436k71 gold badges863 silver badges822 bronze badges

Collectives™ on Stack Overflow

Check that a string exists within another string with regular expression

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related