正则表达式清理字符串

Question

I'm struggling to figure out even where to start with this. I believe there is a regular expression to make this a fairly straight forward task. I want to trim off the extra asterisks in a string.

Example string:

test="AM*BE*3***LAST****~"

I would like it to trim asterisks off only the end that don't have repeating symbols. So the resulting value in the variable would be:

test="AM*BE*3***LAST~"

In Perl I was able to use this:

s/\*+~+/~/;

Is there something similar I can do in Ruby? I'm sure there is, just struggling to find it for some reason. Any help would be greatly appreciated.

Answer 1

You could use this regex:

/\*+~$/

Then use the gsub method to replace all matches with a tilde ~ :

test = "AM*BE*3***LAST****~"

test.gsub!(/\*+~$/, '~')
# => "AM*BE*3***LAST~"

Or you could use this more flexible regex, which matches any amount of characters after * until end of line:

/\*+([^*])+$/

Then use the first capture group ( $1 ) as the replacement:

test.gsub(/\*+([^*])+$/) { $1 }

Answer 2

Ruby's String class has the [] method, which lets us use regexp as a parameter. We can also assign to that, allowing us to do things like:

foo = "AM*BE*3***LAST****~"
foo[/\*+~+$/] = '~'
foo # => "AM*BE*3***LAST~"

That reuses the match pattern from your Perl search/replace. (I'm assuming you only want to match at the end of the line because of your examples. If it needs to be anywhere in the string remove the trailing $ from the pattern.)

Answer 3

You can use Rubular and try to test the regex and achieve what you need based on the references down the page.

http://rubular.com/