in reply to foreach (each character in string..)?

A couple other ways that don't make an arrayconstruct a list in memory of all the characters: 
for my $i (0..length($string)-1) {
    # whatever with substr($string, $i, 1)
}

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or 
while ($string =~ /./gs) {
    # whatever with $&
    # note that this incurs the penalty for using $&
}

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Re: Re: foreach (each character in string..)?
by Aragorn (Curate) on Jan 20, 2004 at 21:14 UTC 
    while ($string =~ /./gs) {
    # whatever with $&
    # note that this incurs the penalty for using $&
}
    You can avoid the $& penalty by using parentheses: /(.)/gs and using the $1 variable.

    Arjen

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      You can avoid the $& penalty by using parentheses: /(.)/gs and using the $1 variable.

      Just to clarify ... you can avoid the $& penalty on all your other regular expressions, but you still pay it on this one (only its name is changed to $1)

      duff

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Re: Re: foreach (each character in string..)?
by revdiablo (Prior) on Jan 20, 2004 at 20:20 UTC

    I tried to send you a /msg, but I am unsure how to do so due to the space in your username. I have a quick pedantic note: you should probably s/array/list/ on your first sentence. 8^)

    Even more pedantic is to point out that 0..length($string)-1 does indeed make a list, but I think we know what you meant. ;)

    Update: I stand corrected. It might be noted that I knew there was an optimization with for and the range operator, but I thought it still ended up building a list -- I didn't realize it just turned into an iterator.

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      Yes, I am a bit loose in calling lists arrays. But note that in a foreach, the .. operator with integer operands does NOT create a list. It acts as an iterator. This is a special optimization introduced in 5.005.
      The PerlMonk tr/// Advocate
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