Re: How do I quickly strip blank space from the beginning/end of a string?

[ikegami]

Your solutions are very broken.

• All of your solutions require the last non-space character to be an uppercase letter. You could say you're investigating a subset of the original question, except that your input has no uppercase letters. Use \s or a space instead of [^A-Z]. Use \S instead of [A-Z].

• Some of your solutions have problems with trailing newlines due to the missing "s" modifier. /./ doesn't match newlines without it.

• All but the last of your solutions don't work if the input is made entirely of spaces.

There's also a issue with your benchmark. Benchmarking code that removes trailing spaces when your input never has trailing spaces is odd. Include a case where the input has trailing spaces!

[blahblahblah]

You're right, in my haste to get this question out there I made the jump from my original problem to japhy's post to talking about his benchmarks. One of my coworkers pointed out the same thing to me as I was headed out the door. Obviously I should be benchmarking the exact problem I want to solve, not some generally similar example. After I get the kids to bed I'll write a better benchmark and try your \K suggestion below too. Thanks.

Also, you made the point that none of my input ends with spaces. I think that's generally true in real life usage too. It's frustrating that we have this pervasive idiom in our code of "strip whitespace just in case", but I think most of the time the input is already just fine. In fact, I think much of the time the input is short and has no spaces at all. I wonder if I should be checking it with index() first to quickly rule out that case.

update: added paragraph spacing

[ikegami]

Also, you made the point that none of my input ends with spaces. I think that's generally true in real life usage too.

Then shouldn't you be benchmarking space detection?

[blahblahblah]

Good point. I've tried the 3 methods below:

if ($x =~ /\s/)

and

if (substr($x, -1) =~ /^\s/

and

if (rindex($x," ") == 0 || rindex($x,"\r") == 0 ||  rindex($x,"\n") ==
+ 0 ||  rindex($x,"\t") == 0)

The rindex method is much faster on the data that has spaces; otherwise the substr method is the fastest. Any other good ideas, keeping in mind that the data (I think) won't often contain any trailing spaces?