rsFalse has asked for the wisdom of the Perl Monks concerning the following question:

Once I read and split line of two big numbers. And then I divided one to another. I got not integer value. Later I simplified to this code: 
use bigint;

print ("10" / "3");
$n="3";
print ("10" / ++$n);
print ("10" / $n);
$n+="0";
print ("10" / $n);
$n+=0;
print ("10" / $n);
$n.="";
print ("10" / $n);

[download]
Compare integer and bigint;

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Re: is it a BigInt bug?
by graff (Chancellor) on Jul 19, 2014 at 21:49 UTC
    To put it more simply, I gather you are asking about the difference between these two cases: 
    perl -Mbigint -wle '($x,$y)=split " ","9 2"; $z = $x / $y; print $z'
4.5

perl -Mbigint -wle '($x,$y)=map {$_+= 0} split " ","9 2"; $z = $x / $y
+; print $z'
4

    [download]
    The manual for bigint says "Integer constants are created as proper BigInts. Floating point constants are truncated to integer."

    It doesn't say anything about interpolating strings into "proper Bigints", so… while this behavior does seem to go against the spirit of DWIM, it's not officially a bug if strings have to be coerced explicitly into numbers in order for them to become bigints.

    Or was there some other issue that you were trying to describe?

[reply]
[d/l]
      Thank you, graff, it was what I mean. I thought it must DWIM, and "use bigint" must not work in different way from "use bigint". I found real number instead of integer in this case at the bottom, later wrote here. 
      use bigint;
($m,$k)=split/ /,<>;
print $k<$m? $m / ++$k : -1

      [download]
      stdin="10 2\n" stdout=3.33... One more strange is that increment of "2\n" did not change it to a number.
[reply]
[d/l]
        increment of "2\n" did not change it to a number.

        Why do you say that?

        13:45 >perl -Mbigint -wE "my ($m, $k) = split / /, qq[10 2\n]; say qq[
+>$k<]; ++$k; say qq[>>$k<<];"
>2
<
>>3<<

13:49 >

        [download]

        Update (31 Aug 14): Fixed typo: changed ++k to ++$k.

        Auto-increment has here converted $k from a string to a number, as can be seen from the loss of the trailing newline. The same effect is produced by $k++ or $k += 1.

        Hope that helps,

        Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

[reply]
[d/l]
[select]
Re: is it a BigInt bug?
by AppleFritter (Vicar) on Jul 19, 2014 at 21:49 UTC
[reply]

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