Using grep or map to solve this means that you would have to go through the entire length of the array even if the character was at the beginning. Here's a solution that stops as soon as the character is found.

sub foo {
  my ($aChars, $ch) = @_;
  my $i=0;
  for (@$aChars) {
    return $i if $ch eq $_;
    $i++;
  };
}

my @aChars =('a','b','c','d');
print "c=", findChar(\@aChars, 'c'), "\n";
# outputs c=2
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Or if you have an aversion to subs,

my $k='c';
my $i=0;

for (@aChars) { last if $k eq $_; $i++; };

print "$k=$i\n";
#also outputs c=2
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Update:Put in mssing final ';' and patched to print position=array index rather than position = ordinal value. (i.e. c=2 instead of c=3).

  DB<1> @input=('a','b','c','d');
 
  DB<2> %pos= map { $_=>$i++ } @input 
 
  DB<3> print $pos{a}
0
  DB<4> print $pos{d}
3
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... so what if elements aren't unique?

>... so what if elements aren't unique?

since this question hasn't been answered yet here a variation for finding the first idx!

%pos= map { $_=>$i++ } reverse @input;
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If you need it more than once, then the overhead for building a hash will easily pay off.

Cheers Rolf

Try this:

@input=('a','b','c','d');
my $char='b';
print "$char is at position(s): ", 
      join(", ", grep { $char eq $input[$_] } 0..$#input),
      "\n";
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Note: Untested, you keep all the bits if it breaks, etc...

...roboticus

use List::MoreUtils qw(firstidx);
@input=('a','b','c','d');
my $char='b';
print firstidx { $_ eq $char } @input;
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print index(join("",@input),$char);
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Update Seems the example given by the OP led me to a too simplified solution. Thanks for spotting the limitations, LanX

thank god perl arrays can only hold one character strings!

... ;-D

Cheers Rolf

my ($pos) = grep $input[$_] eq $val, 0 .. $#input;
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my ($first, $last) = ({}, {});
@$first{reverse @input} = reverse 0 .. $#input;
@$last{@input} = 0 .. $#input;

my $val = 'b';
print "Last index  : ", $last->{$val};
print "First index : ", $first->{$val};
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my @input=('a','b','c','d');
my $char='b';
# --------------
my $pos = -1;
ELM: for ( my $i = 0; $i <= $#input; $i++ ) {
    if ( $char eq $input[$i] ) {
        $pos = $i;
        last ELM;
    }
}
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