Re: Regular expression: How to determine wether entry is a number?

[myklass@xxxxxxxxx (Aruna Goke)]

Jan-Henrik wrote:
> Dear Group,
>
> I'm new to Perl and I have a simple question:
>
> I ask for the entry of a number vie <STDIN>:
>
> ----------------------------------------
> #!/usr/bin/perl -w
> use strict;
>
> my $foo;
> print "Enter number: ";
> $foo = <STDIN>;
> comp($foo);
> ----------------------------------------
>
> Now I would like to check wether the user really entered a number and
> not letters. What would a check like that look like? A regular
> expression like this:
> ----------------------------------------
> unless ($foo =~ /[a-zA-Z\D+][^.][\D*]/ {...};
> ----------------------------------------
>
> Is there an easier or more beautiful way?
>
> Also, how would I substract just a number from a string? Searched the
> net for an example but didn't succeed, so sorry for asking a question
> like that...
>
> Many thanks for your help!
>
> Kind regards,
>
> Jan-Henrik

#!/usr/bin/perl

use warnings;
use strict;

my $foo;
my $num = 3;
print "Enter number: ";
$foo = <STDIN>;
chomp($foo);

print $foo - $num unless $foo =~ /[a-zA-Z]+/;