in reply to How do I remove whitespace at the beginning or end of my string?
There are some faster solutions which sometimes can be really slow, depending on how many whitespaces a string contain.
If a string contains a lot of whitespaces.
Example: my $str = q{ }. q{a b c d e f g h i j} x 200 . q{ };
MRE book suggests this code:
$str =~ s/^\s+((?:.+\S)?)\s+$/$1/s;
I admit, I was surprised how fast it is compared with: "s/^\s+//" and his brother "s/\s+$//". They can't even compete at a benchmark, they are too slow with the above example! (that's because of the second regex which match at the end of the string, if fails so many times if string contains a lot of whitespaces (see re 'debug')).
Another approach (I know is silly, but is faster in some casses):
If a string contains a lot of whitespaces.
Example: my $str = q{ }. q{a b c d e f g h i j} x 200 . q{ };
MRE book suggests this code:
$str =~ s/^\s+((?:.+\S)?)\s+$/$1/s;
I admit, I was surprised how fast it is compared with: "s/^\s+//" and his brother "s/\s+$//". They can't even compete at a benchmark, they are too slow with the above example! (that's because of the second regex which match at the end of the string, if fails so many times if string contains a lot of whitespaces (see re 'debug')).
Another approach (I know is silly, but is faster in some casses):
Benchmark using the above example:$str =~ s/^\s+//; $str = reverse($str); $str =~ s/^\s+//; $str = reverse($str);
's_reverse' 42017/s -- -12% -48% 'unpack_A' 47847/s 14% -- -41% 'MRE_regx' 80645/s 92% 69% --
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Re: Answer: How do I remove whitespace at the beginning or end of my string?
by repellent (Priest) on Jan 30, 2012 at 00:08 UTC | |
by choroba (Cardinal) on Jan 30, 2012 at 09:04 UTC | |
by repellent (Priest) on Jan 31, 2012 at 05:01 UTC |
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