A simple simulation of the problem:
use strict;
use warnings;
sub uniq
{
my %seen;
grep !$seen{$_}++, @_;
}
my @a = (1, 2, 3, 1, 2);
print shift @{uniq(@a)};
Can't use string ("3") as an ARRAY ref while "strict refs" in use
Need to impose a list context on the function call, and then pick the first element from the list.
The print
, or any other subroutine call, already supplies a list context. Then one way to extract an element from a returned list
print +( func(@ary) )[0];
This disregards the rest of the list.
That +
is necessary (try without it), unless we equip print itself with parentheses around all its arguments, that is
print( (func(@ary))[0] );
One option could be to return an array reference:
sub uniq {
my %seen;
[grep !$seen{$_}++, @_];
}
If uniq
returned an array reference, then @{uniq(...)}
would be the correct idiom to get an array (which is a suitable argument for shift
). For a more general list, you can cast the list to an array reference and then dereference it.
print shift @{ [ uniq(@a) ] };
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