How to solve the following?
use 5.014;
use warnings;
use Test::Simple tests => 4;
ok( doit(0123) == 83, "arg as octal number" );
ok( doit(83) == 83, "arg as decimal number" );
ok( doit('0123') == 83, "arg as string with leading zero" );
ok( doit('123') == 83, "arg as string without leading zero" );
sub doit {
my $x = shift;
return $x; # how to replace this line
#return got_the_arg_as_string ? oct($x) : $x; # with something like this
}
E.g. If i pass to the doit sub any string - mean quoted value - (with or without the leading zero), it should be converted to octal value. Otherwise, it is just an number.
Perl's internal representation of a scalar may be as in integer or a string, and it remains ready to coerce that representation into any other scalar type at any moment. It is possible with C/XS code to get at a scalar's internal type. The JSON::XS module does this, for example, to decide whether a value should be rendered as a number or as a string.
Here's a proof of concept for your problem:
use Inline 'C';
sub foo {
my ($x) = @_;
print $x, " => isString: ", isString($x), "\n";
}
foo(0123);
foo('0123');
__END__
int isString(SV* sv)
{
return SvPOK(sv) ? 1 : 0;
}
Program output:
83 => isString: 0
0123 => isString: 1
Related posts:
Difference between $var = 500 and $var = '500'
When does the difference between a string and a number matter in Perl 5?
Why does the JSON module quote some numbers but not others?
Update some of this functionality is exposed in the core B module, so no need to add as XS dependency:
use B;
sub isString {
my $scalar = shift;
return 0 != (B::svref_2object(\$scalar)->FLAGS & B::SVf_POK)
}
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