esn.pl

Category:	Utilities
Author/Contact Info	DeFyance -=at=- comcast.net defyance
Description:	A simple esn converter. Its pretty crappy code, I am posting it here, in hopes that someone can come up with a better/more efficient/prettier way to do this..
#!/usr/bin/perl -w use strict; #Lets convert that ESN print "\n\n", "" x22, "\n"; print "ESN Converter v.01", "\n"; print "" x22, "\n"; print "Please enter ESN:"; chomp( my $hexnum = <STDIN> ); push (my @hexnum, $hexnum); @hexnum = split ( ' ', $hexnum ); if ( $hexnum eq "" ) { print "Invalid Input!\n"; print "Press <ENTER> to continue";<>; } else { go(@hexnum); } sub go { if ( length( $hexnum[0] ) == 8 ) { my $mfg = hex( substr( $hexnum, 0, 2 ) ); my $serno = hex( substr( $hexnum, 2, 6 ) ); printf( "\nDecimal: %d %d\nHex: %s\n\n", $mfg, $serno, $hexnum + ); print "Press <ENTER> to continue";<>; } elsif ( length( $hexnum[0] ) == 3 ) { printf( "\nDecimal: %3d %8d\n", $hexnum[0], $hexnum[1] ); printf( "Hex: %2X%6X\n\n", $hexnum[0], $hexnum[1] ); print "Press <ENTER> to continue";<>; } else { die "Invalid Input!\n"; print "Press <ENTER> to continue";<>; } }

Comment on esn.pl Download Code

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Re: esn.pl
by graff (Chancellor) on Aug 27, 2002 at 06:03 UTC

you're putting the same entry into @hexnum two times, in two different ways, and the latter is simply negating the former:
```
    push (my @hexnum, $hexnum);
    @hexnum = split ( ' ', $hexnum );
[download]
```
One or the other of these will do, but don't do both. (It seems like the latter is better given the current "user interface" -- especially if you give the user a clue that the script will accept multiple esn's on one line of input, separated by spaces -- in that case, just use:
```
    $_ = <STDIN>;
    @hexnum = split;
[download]
```
You pass @hexnum to the "go" sub, but the sub never checks its parameter list -- it just looks at the global @hexnum; you can do it either way, but it makes no sense doing it both ways at once. (Most folks would recommend passing parameters -- else, why have a subroutine at all?
```
sub go {
   my @esns = @_;
   ...
}
[download]
```
Your checks on the input are not going to be effective for a variety of unusable strings that the user might type in.

And of course the whole thing can be done more compactly and simply:

use English;

if (@ARGV and $ARGV[0] eq "-v") {
    shift;  # crude method for option handling (cf. Getopt::Std)
    print STDERR "ESN Converter v.02\n"; # report version when asked
}  # (otherwise, keep quiet about that)

unless (@ARGV and -r $ARGV[0]) { # if no file name, go interactive
    print STDERR "Usage: $0 [esn_list.filename]\n";
    $eof = ( $OSNAME =~ /.n.x$/ ) ? "^D" : "^Z";
    $prompt = "Please enter an ESN string (or $eof to exit): ";
    print STDERR $prompt;
}

while (<>) {
    s/\s+//g;  # start by eliminating all whitespace
    unless ( /^([0-9a-f]{2})([0-9a-f]{6})$/ ) {
       print STDERR "skipped input string $_ : not a valid ESN\n";
       next;  # only accept 8-digit hex strings
    }
    ($mfg,$serno) = (hex $1, hex $2);
    printf( "Hex: %s == Decimal: %d %d\n",$_,$mfg,$serno);
} continue {
    print STDERR $prompt if $prompt;
}
[download]

Printing prompts, version and error messages to STDERR makes it easy to redirect valid results to a file, since that might be a useful feature.

Other approaches are possible and could be better, but this seems close to your original intent.

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