Which version of Perl are you using?

IWFM

#!/usr/bin/perl -w
use strict;

printf "Perl %vd\n",$^V;

while(<DATA>){

    print  $_;
    for my $letter ('a' .. 'z') {
        my $index = index($_,$letter);
        next if $index < 0;
        print  "The first occurence of '$letter' is: ", $index, "\n";
    }
    print  "\n\n";
}

__DATA__
ATGGACTGCACCTGGAGGATCCTCTTCTTGGTGGCAGCAGCTACAGgcaagagaatcctgagttccaggg
+ctgatgaggg
[download]

Output:

Perl 5.6.1
ATGGACTGCACCTGGAGGATCCTCTTCTTGGTGGCAGCAGCTACAGgcaagagaatcctgagttccagggctgatgaggg
The first occurence of 'a' is: 48
The first occurence of 'c' is: 47
The first occurence of 'g' is: 46
The first occurence of 't' is: 55


Perl 5.8.4
ATGGACTGCACCTGGAGGATCCTCTTCTTGGTGGCAGCAGCTACAGgcaagagaatcctgagttccagggctgatgaggg
The first occurence of 'a' is: 48
The first occurence of 'c' is: 47
The first occurence of 'g' is: 46
The first occurence of 't' is: 55