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RE: Baby Steps

by flyfishin (Monk)
on Jun 22, 2000 at 23:47 UTC ( #19495=note: print w/replies, xml ) Need Help??

in reply to Baby Steps "if" behavior?

If I remember correctly 0, null string, and empty string are all false answers. However, 0 and empty string are defined answers. $kaka ne "" checks to see if $kaka is equal to the empty string. Whereas defined $kaka checks to see if $kaka is something other than 0, null, or empty. I also think there are some differences for defined and exists. I think exists only applies to hash values. I know this isn't a complete answer but it gets you pointed in the right direction, I hope. Check in perlfunc for more complete answers.

Oops. You can uses exists to check on array elements. Next time I'll read perlfunc before shooting off with the fingers.

Replies are listed 'Best First'.
RE: RE: Baby Steps
by sean (Beadle) on Jun 23, 2000 at 04:04 UTC
    Well... defined $kaka actually checks to see if $kaka is defined at ALL. something that is defined as zero, null, or empty is still defined.
    sean@anticharm:~$ perl -e 'print "defined!\n" if defined $foo' sean@anticharm:~$ perl -we '$foo = 0; print "defined!\n" if defined $f +oo' defined! sean@anticharm:~$ perl -we '$foo = ""; print "defined!\n" if defined $ +foo' defined!
    As far as I am aware, once you define something you must use undef (or assign it the value of something undefined: undef $baz; $foo=$baz;) if you want it to be undefined again.
RE:(2) Baby Steps (exists on array)
by Russ (Deacon) on Jun 23, 2000 at 03:15 UTC
    Using exists on an array is a new feature in 5.6

    For those of us too lazy (busy) to upgrade, you were right. :-)


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