Trim string using reqex match

Question

I have to use a crippled tool which doesn't provide any way to trim leading an trailing spaces from a string. It does have .NET style regex, but only Match is implemented, not replace. So, I came up (surprisingly by myself) with this regex that seems to work.. but I don't completely understand why it works :-)

$trimmed = regex/[^ ].*[^ ]/ ($original_string)

Why does this work, does it really work in all cases, and is there a better way if you only have regex Match ( even group matches can't be captured :( ) ?

Answer 1

It should work fine unless there's only a single character surrounded by space.

Your pattern searches for:

1. A non-space character [^ ]
2. Zero or more characters of any kind, as many as possible (greedy match) .*
3. A non-space character [^ ]

So, if there aren't at least two non-space characters (1 and 3), the pattern won't match at all.

You should use \b instead of [^ ], that will match any 'word boundary', but will be of zero length and won't require two non-space characters:

\b.*\b