in reply to grep surprise

RTFM?

grep

In scalar context, returns the number of times the expression was true.

and it's $i3 not i3

anyway others may profit from a working solution, just replacing grep with first 

use strict;
use warnings;
use List::Util qw/first/;


my @array=(1,2);

my $i1 = first { $array[$_] == 1 } (0..$#array);
my $i2 = first { $array[$_] == 2 } (0..$#array);
my $i3 = first { $array[$_] == 3 } (0..$#array);

print "<$i1> <$i2> <$i3>\n";

[download]
Use of uninitialized value $i3 in concatenation (.) or string at d:/tm
+p/first.pl line 13.
<0> <1> <>

[download]

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

Replies are listed 'Best First'.
Re^2: grep surprise
by morgon (Priest) on Nov 11, 2018 at 23:52 UTC
    ikegami shows the way to do it above.

    Using List::Util::first works of course but does not add any value at all.

[reply]
      > does not add any value at all.

      Not very surprising that you think that way.

      Cheers Rolf
      (addicted to the Perl Programming Language :)
      Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

[reply]
        How about the value of verbosity? 
        $ perl -we '
use strict;
my @array=(1,2);
my $matches = 0;
for my $ea (1..3) {
  $matches = grep {
    printf("idx: %d, val: %d == %d? %3s, ",
      $_, $array[$_], $ea, ($array[$_] == $ea) ? "YES" : "NO");
    $array[$_] == $ea; 
  } (0..$#array);
  print "matches: $matches\n";
}
'

__output__
idx: 0, val: 1 == 1? YES, idx: 1, val: 2 == 1?  NO, matches: 1
idx: 0, val: 1 == 2?  NO, idx: 1, val: 2 == 2? YES, matches: 1
idx: 0, val: 1 == 3?  NO, idx: 1, val: 2 == 3?  NO, matches: 0

        [download]

        and who ever said Perl was not readable... :)

[reply]
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