in reply to fibo's 66 chars

I agree, very nice. If you're golfing this, I have a few reductions for you:

You can save yourself a couple of characters by using pop instead of shift.

Also, if you use -l, you can get rid of the quotes and newline:
$a=pop;@b=(0,1);push@b,$b[-2]+$b[-1]while$#b<$a;print$b[-2]

Then, you can cut down the while$#b<$a by using for(2..$a):
$a=pop;@b=(0,1);push@b,$b[-2]+$b[-1]for(2..$a);print$b[-2]

Of all the causes that conspire to blind
Man's erring judgment, and misguide the mind,
What the weak head with strongest bias rules,
Is pride, the never-failing vice of fools.
-- Pope.

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Re^2: fibo's 66 chars
by Roy Johnson (Monsignor) on May 27, 2009 at 21:17 UTC
    Since you only use the parameter once, it's cheaper to just reference it as $ARGV[0] pop it inline rather than assign it to anything. 
    @b=(0,1);push@b,$b[-2]+$b[-1]for 2..pop;print$b[-2]

    [download]
    You can save fourteen more strokes (and, irrelevantly, memory) by not using an array and using convoluted scalar assignment with a variable that is pre-initialized: 
    $b=1;$?=($b+=$?)-$?for 2..pop;print$?

    [download]
    Caution: Contents may have been coded under pressure.
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