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Re^3: Numification of strings

by ww (Bishop)
on Aug 02, 2010 at 12:33 UTC ( #852462=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Numification of strings
in thread Numification of strings

"but it's only about converting undef"

Lest you or anyone else read that as generally true, I repeat, for emphasis re warnings (or for brevity here, -w) and re 'consistent':

perl -we "$x="LanX"; print ($x * 3);" Argument "LanX" isn't numeric in multiplication (*) at -e line 1. 0 perl -we "$x="LanX"; print ($x % 3);" Argument "LanX" isn't numeric in modulus (%) at -e line 1. 0 perl -we "$x="LanX"; print (3^$x);" Argument "LanX" isn't numeric in bitwise xor (^) at -e line 1. 3 perl -we "$x="LanX"; print (3**$x);" Argument "LanX" isn't numeric in exponentiation (**) at -e line 1. 1

but

perl -we "$x='7LanX'; print (3^$x);" Argument "7LanX" isn't numeric in bitwise xor (^) at -e line 1. 4 perl -we "$x='7LanX'; print ($x*3);" Argument "7LanX" isn't numeric in multiplication (*) at -e line 1. 21 perl -we "$x='7LanX'; print (3**$x);" Argument "7LanX" isn't numeric in exponentiation (**) at -e line 1. 2187

and where it's useful -- using a string as a number because it's being used in an operation which is arithmetic:

perl -we "$x=\"5\"; print ($x*3);" # 2 15 perl -we "$x='5'; print ($x*3);" 15

2   Interesting (or not enough coffee yet?): doze balked at doublequotes without escapes here, but passed 'em cheerfully above. WTF?


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Re^4: Numification of strings
by LanX (Canon) on Aug 02, 2010 at 12:52 UTC
    > > "but it's only about converting undef"

    converting undef is differently handled with ++, enabling warnings doesn't help here!

    see Re^3: Numification of strings

    Cheers Rolf

      More like "doesn't hurt".
      ++$count{$_} for @list;
      would have to be written
      $count{$_} = $count{$_}//0 + 1 for @list;
      if warnings had an effect.

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