If you really want to go with this sort of "extended dialog" via stdin, you should check out Term::ReadLine.

Here's one way to structure things so that the coding is easier. (I'm just going with basic usage in this example - the module has various options and extra methods to make things easier for the person who is typing, such as keeping a history of responses, so they can be recalled and reused, etc. Notice that Term::ReadLine strips off the newline characters for you.) 

#!/usr/bin/perl

use strict;
use warnings;
use Term::ReadLine;

my $term = Term::ReadLine->new();
my @prompts = ( "the starting amount",
                "your current age",
                "the age you want to retire",
                "amount deposited per year",
                "the annual interest rate",
                "expected retirement money" );
my %responses;

for my $prompt ( @prompts ) {
    my $response = '';
    until ( $response =~ /^\d+$/ ) {
        $response = $term->readline( "Enter $prompt: " );
        last unless defined( $response );
        if ( $response =~ /\D/ ) {
            warn "Numeric answers only, please.  Try again.\n";
        }
        elsif ( $prompt eq "the age you want to retire" and
                $response < $responses{"your current age"} ) {
            warn sprintf( "We can't change the past. Give me a number 
+> %d\n",
                          $responses{"your current age"} );
            $response = "";
        }
    }
    $responses{$prompt} = $response if ( defined( $response ));
}

printf "\nThank you for your %d answers\n", scalar keys( %responses );
for ( @prompts ) {
    print "  $_ : $responses{$_}\n" if ( exists( $responses{$_} ));
}

[download]
(There are different "flavors" of Term::ReadLine that you can use; your perl version probably has a "default" version that will suit your needs.)

In reply to Re: Stdin for just numbers. by graff
in thread Stdin for just numbers. by programmercarlito

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