in reply to adding 1 to a char of 1

Perl is designed to make string and numeric scalars indistinguishable. It also has a '++' (increment) operator which not only works on numerical strings as well as numbers, but on any string. e.g.
$x = 1; ++$x; # produces 2 or "2" (transparent which)
$x = "1"; ++$x; # the same
$x = "A"; ++$x; # produces B

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To strip leading zeros: 
$char =~ s/^(0)+//;

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see the perlop documentation for more details.

-M

Free your mind

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Re^2: adding 1 to a char of 1
by Anonymous Monk on Jun 20, 2006 at 17:38 UTC
    Thanks everyone for your help, it works fine now.... One last question.... now that I have the correct number, how do I only grab the last 4 digits so for example: 
    my original number was 9 but now with the code u guys gave me, we incr
+emented into 10. I need to plug this number back into the file name b
+ut creating a new file called "name_0010" (originally it was "name_00
+09"). Here is the code I currently have, I know theres a more efficie
+nt way to do this...

$newfile = substr($newfile_n,0, 4);
$newfile =~ s/^(0)+//;
++$newfile;
print"$newfile\n";
$newfile = "000".$newfile; #if it gets to 100 then it will look like t
+his "0100"
substr($newfile, 1, 4);

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[d/l]
      Not sure why you're using substr.  Let me suggest that you keep the index and the basename separate.

      For example: 

      my $index = 0;
for (my $i = 0; $i < 100; $i++) {
    $index++;
    my $fullname = sprintf "base_%04d", $index;
    printf "fullname = '%s'\n", $fullname;
}

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      will print 100 different names, starting with "name_0001" and ending with "name_0100".  The %04d achieves this result; the "0" left-pads the integer value with zeroes, and the "4" gives you 4 decimal places.

      Read up on sprintf to get more details:  perldoc -f sprintf.

      If you absolutely must get the last 4 digits of a string, you can use "substr" like this: 

      $last_4_chars = substr($my_string, -4);

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      This has the effect of taking the "rest" of the string, starting at the 4th character from the end (since the offset -4 is negative) rather than from the beginning.

      s''(q.S:$/9=(T1';s;(..)(..);$..=substr+crypt($1,$2),2,3;eg;print$..$/
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        Great thats exactly what I was looking for.... Thanks to all u wisemen and women...
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      Use substr to extract and replace: 

      my $oldfile = "name_0009";
my $num = substr($oldfile, -4);
++$num;
my $newfile = substr($oldfile, 0, -4) . $num;

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      Or use the lvalue form to simplify things: 

      my $oldfile = 'name_0009';
substr(my $newfile = $oldfile, -4)++;

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