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How can I strip an arbitary number of leading spaces from a string?

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Contributed by Zombie parsec on Sep 25, 2000 at 20:00 UTC
Q&A  > strings


Answer: How can I strip an arbitary number of leading spaces from a string?
contributed by japhy

There is no need to use s/^\s*//. This will waste time on strings with no leading space. Use s/^\s+// at all times -- it obviously won't do anything if there's no whitespace to match.

A general rule of thumb is that s/X*// is slower than s/X+//, and in cases where the RHS (right-hand side) is something OTHER than "", chances are you really do mean X+.

Answer: How can I strip an arbitary number of leading spaces from a string?
contributed by chromatic

Use a regex with a quantifier. Use this one if you're not sure there will be any spaces at the start of the string:

$string =~ s/^\s*//;

Use this one if you know there will be at least one:

$string =~ s/^\s+//;

{QA Editors note: As japhy pointed out, the "+" quantifier is preferable over the "*" quantifier, even if it's unknown whether the string being tested has leading whitespace or not. With s/^\s+//;, strings lacking leading whitespace simply will be passed over. Furthermore, the "+" quantifier is faster than the "*" quantifier.}

Answer: How can I strip an arbitary number of leading spaces from a string?
contributed by Anonymous Monk

$string =~ s/^\s+//gm; this will start at the beginning and only continue as long as there is whitespace left at the beginning of the string.

Answer: How can I strip an arbitary number of leading spaces from a string?
contributed by Zombie parsec

OK, silly me, that didn't take very long to figure out:

$string = <>; $string =~ s/ *//;

Edit by Corion
This answer is maybe sufficient, if every string contains at least one space. If one of your strings does not contain a space, it will remove spaces from the middle or the end of the string. Please have a look at chromatics post for a correct answer.

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