in reply to "2" | "8" = ":" and 2|8=10

I think that if I *really* did need to know whether the variable had one of the numeric flags set, then I'd probably use an XSub ... something like: 
use warnings;
use strict;

use Inline C => Config =>
    BUILD_NOISY => 1;

use Inline C =><<'EOC';

int is_num(SV * x) {
    if(SvIOK(x) || SvUOK(x) || SvNOK(x)) return 1;
    return 0;
}


EOC

my $ui = ~0;

print is_num(2), "\n";
print is_num("2"), "\n";
print is_num($ui), "\n";
print is_num("$ui"), "\n";
print is_num(2.3), "\n";
print is_num("2.3"), "\n";

[download]
I know how to force a string to an integer using int()

The usual way to force numeric context is to add 0 (as already demonstrated) or multiply by 1. Using int() will truncate fractional values, thereby altering them.

Cheers,
Rob

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Re^2: "2" | "8" = ":" and 2|8=10
by ikegami (Patriarch) on Nov 04, 2011 at 20:19 UTC

    Note: This doesn't take magic into account. The bitwise ops sure do. 

    print is_num($|), "\n";   # 0
$|=1;
print is_num($|), "\n";   # 0
print 1   | "A", "\n";
print "1" | "A", "\n";
print $|  | "A", "\n";    # Acts as if $| is numeric

    [download]

    Note: SvUOK(x) will always be false if SvIOK(x) is false, and SvNIOK(x) is more efficient than SvIOK(x) || SvNOK(x).

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