There are reasons to worry, most notable with regards to the bitwise operands, &, |, ^, ~ on one hand, << and >> on the other. And % also has a limit on the range for which it works reliable — very system dependent, I've had a perl 5.005 for which modulo calculations with a number > 2**32 always returned zero, but on my newer port, I can go up to 2**52 or 2**53 (I don't recall exactly), the mantissa part of an IEEE double float, of 64 bits.

This meaningfulness does give a clue on how to efficiently test how large the range can be: I'm quite convinced the limit is always closely related to a power of 2 so one could shift a number to the left, until the result differs from the number times 2, in floating point calculation. 

my $i = 0;
my $n = my $m = 1;
while($n == $m) {
    $n <<= 1;
    $m *= 2;
    $i++;
}
print "different for $m (2**$i)\n";

[download]
I get: 
different for 4294967296 (2**32)
What precisely this implies, I leave as an exercise for the reader. :)

In reply to Re: Re: How to portably determine integer limits? by bart
in thread How to portably determine integer limits? by Anonymous Monk

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