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In exercise 3-3 from the lama book.

How do you make sure the user enters a number 1 thru 7?

The simple program is:

#!/usr/bin/perl
use warnings;
use strict;
my @names = qw/ fred betty barney dino wilma pebbles bamm-bamm /;
print "Enter some numbers from 1 to 7, one per line, then press Ctrl-Z:\n";
chomp(my @numbers = );
foreach (@numbers) {
print "$names[ $_ -1]\n";
}

Just curious.. Thanks.

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Re: <STDIN>

On Mon, 5 Sep 2011 14:10:35 -0500
Chris Stinemetz wrote:

> In exercise 3-3 from the lama book.
>=20
> How do you make sure the user enters a number 1 thru 7?
>=20
> The simple program is:
>=20
> #!/usr/bin/perl
> use warnings;
> use strict;
> my @names =3D qw/ fred betty barney dino wilma pebbles bamm-bamm /;
> print "Enter some numbers from 1 to 7, one per line, then press Ctrl-Z:\n=
";
> chomp(my @numbers =3D );
> foreach (@numbers) {
> print "$names[ $_ -1]\n";
> }
>=20

One option would be to check that $_ matches the regular
expression /\A[1-7]\z/ , where \A is the start of the string, [1-7] is any
character from 1 to 7 and \z is the end of the string. So your program beco=
mes:

#!/usr/bin/perl

use warnings;
use strict;

my @names =3D qw/ fred betty barney dino wilma pebbles bamm-bamm /;
print "Enter some numbers from 1 to 7, one per line, then press Ctrl-Z:\n";
chomp(my @numbers =3D );
foreach (@numbers) {
if ($_ =3D~ /\A[1-7]\z/) {
print "$names[ $_ -1]\n";
}
else {
warn "Incorrect number - '$_'";
}
}

I should also note that one would use Ctrl+D instead of Ctrl+Z for EOF in
UNIX-land.

Regards,

Shlomi Fish

> Just curious.. Thanks.



--=20
------------------------------------------------------------ -----
Shlomi Fish http://www.shlomifish.org/
Funny Anti-Terrorism Story - http://shlom.in/enemy

Chuck Norris is his own boss. If you hire him, heâ€=99ll tell your boss=
what to
do.

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Re: <STDIN>

>
> I should also note that one would use Ctrl+D instead of Ctrl+Z for EOF in
> UNIX-land.
>

Thank you Shlomi. I am currently in the windows-land.
I was not aware of the warn function. Learn something new everyday!

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Re: <STDIN>

On 11-09-05 03:22 PM, Shlomi Fish wrote:
> One option would be to check that $_ matches the regular
> expression /\A[1-7]\z/

Another is to write a sub you can re-use:

#!/usr/bin/env perl

use strict;
use warnings;

use Scalar::Util qw( looks_like_number );

sub choose_from_menu {
my ( @menu ) = @_;
my %choice = (); # get unique list of choices

# do loop forever, i.e. until exited by last
GET_ITEM_CHOICES:
while(1){

# prompt for input
print "\nEnter the number(s) of your choice:\n";
print "Press Ctrl-Z to signify you have finished inputting your
list.\n\n";

# display the menu, with a number for each item
my $index = 1;
for my $item ( @menu ){
printf "\t% 2d. %s\n", $index, $item;
}continue{
$index ++;
}

# can get only one choice at a time
print "\n\tEnter your choice: ";
my $anything = ;

# if STDIN is undef, user pressed Ctrl-Z
last GET_ITEM_CHOICES unless defined $anything;

# $anything should be all digits
chomp( $anything );

# validate the user's choice
if( looks_like_number( $anything )
&& $anything >= 1
&& $anything <= @menu
){

# it's a valid number
my $number = $anything - 1;

# has it been enter before?
if( exists $choice{ $number } ){
warn "\n\n***** '$anything' is already choosen *****\n\n\n";
}else{
$choice{ $number } = 1;
}

}else{ # not a valid number
warn "\n\n***** '$anything' is not a numbered item in the list
*****\n\n\n";
}
}

# make output more readable
print "\n\n\n";

# return choices sorted as numbers
return sort { $a <=> $b } keys %choice;
}

# list of names for testing
my @names = qw/ fred betty barney dino wilma pebbles bamm-bamm /;

# call the sub
my @choosen = choose_from_menu( @names );

# show the results
print "names choosen: @names[@choosen]\n";

__END__




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