http://qs321.pair.com?node_id=10974

Buckaroo Buddha has asked for the wisdom of the Perl Monks concerning the following question:

I've tried: 
$start = $ARGV[0];

if ($start eq '') {
    $start = &get_start_level;
}
sub get_start_level {
    print "Please Enter the Start-Level (0-7,?)[0]: ";    
    $input = <>;
    # clear all but numbers or '?'
    #if ($input ne '?') {
    #    $input =~ tr/!(0-9)//\d;
    #}
    
    if ($input eq '?') {
      print " **** internally coded help information  **** \n";
    print " **** internally coded help information  **** \n";
    $input = &get_start_level;
    } elsif (($input < 0) || ($input > 7)) {
    print "please enter a number that is between Zero and Seven\n";
    $input = &get_start_level; 
    }
    return ($input);
}
  =========================== end code  ============

[download]
This seems to me like a pretty straight forward problem. What am i doing wrong? ... I can't seem to figure this out.

Originally posted as a Categorized Question.

Replies are listed 'Best First'.
Re: How can I validate user input?
by ton (Friar) on Apr 05, 2001 at 03:56 UTC 
    while ($start !~ /^[0-7]$/) {
    print "Please Enter the Start-Level (0-7,?)[0]: ";    
    $start = <STDIN>;
    chomp $start;
    if ($start eq '?') {
        print "Some help info.\n";
    }
}

    [download]
[reply]
[d/l]
Re: how do i work this
by Russ (Deacon) on May 12, 2000 at 06:17 UTC
    Here's one way to do this: 
    my $start = $ARGV[0];

while (1){
  print "Please Enter the Start-Level (0-7,?)[0]: ";
  chomp($start = <>);

  # Check for non-numeric characters
  if ($start =~ /\D/){
    print "\nPlease enter a number (0-7) or ? for help\n";
    next;
  }

  last if 0 <= $start and $start <= 7;

  # Check for a help request
  if ($start eq '?') {
    print " **** internally coded help information **** \n";
    next;
  }

  print "\nPlease enter a number between Zero and Seven, inclusive\n";
}

print $start;

    [download]
    First, we check that the input is numeric (as you started to do in your commented-out code) to prevent errors if the user enters non-numeric characters.
    If the input is valid, we just exit the loop.
    If not, check for a help request and, if not '?', print a generic error message and redo the loop.

    There are a million different ways to do this, and this is only one of them...

    Russ

[reply]
[d/l]

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