ruby regex - how to match everything up till the character -

Question

given a string as follow:

randomstring1-randomstring2-3df83eeff2

How can I use a ruby regex or some other ruby/rails friendly method to find everything up until the first dash -

In the example above that would be: randomstring1

Thanks

Solution 1

You can use this pattern: ^[^\-]*

Solution 2

mystring = "randomstring1-randomstring2-3df83eeff2"
firstPart = mystring[0, mystring.index("-")]

Otherwise, I think the best regex is @polishchuk's.

It matches from the beginning of the string, matches as many as possible of anything that is not a dash -.

Solution 3

Using irb you can do this too:

>> a= "randomstring1-randomstring2-3df83eeff2"
=> "randomstring1-randomstring2-3df83eeff2"
>> a.split('-').first
=> "randomstring1"
>> 

Solution 4

For this situation, the index solution given by agent-j is probably better. If you did want to use regular expressions, the following non-greedy (specified by the ?) regex would grab it:

(^.*?)-

You can see it in Rubular.

View more solutions

Comments

[JBB]

Tsk...Extra backslash. :) Dash doesn't need to be escaped when it's the first character in a character class (the opening caret doesn't count as a character in the class, it's a class modifier, specifically meaning "Not" as in "Not any of these characters in this class"

[Kirill Polishchuk]

@JBB, I agree, my habit... :-)

[Brad]

Could you explain why this works? I didn't realize you could use the caret twice.

[Kirill Polishchuk]

@Brad, 1st caret is "beginning of the string". [^\-] means any character except -.

[Brad]

@KirillPolishchuk Thanks, I understand the beginning of a string part but I don't understand how it's used twice here. Does this mean that [^\-]* means any string that doesn't start with -?

[Kirill Polishchuk]

@Brad,no, it will just grab first matching string. Try to remove the first ^. In this case reges matches randomstring1, randomstring2 and 3df83eeff2