Perl and Terminal w/OS 10.5.5

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Level 1

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Perl and Terminal w/OS 10.5.5

I am studying Perl as a total newbie and trying to write a simple Perl program to ask for User Input. However, I don't know how to test that in Terminal - where does the User input his or her name, for instance? I wrote this code, but don't know if it's close to right, as I don't know how to test it since it asks for user variables. Any help would be much appreciated.

'print "What is your last name?\n";
$lastname = <STDIN>;
print "What is your first name?\n";
$firstname = <STDIN>;
print "Please enter three single digits numbers separated by commas.\n";
@numbers= <STDIN>;
print "You entered '@numbers'.";
$firstinitial=index("$firstname", 0, 1);
print "Your user name is '$lastname$firstinitial'.\n";
print "Your password is ('@numbers', 2, 1, 0)";'

Thanks,
Karen

MacBookPro 15", Mac OS X (10.5.5)

Posted on Oct 27, 2008 11:57 PM

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Answer 1

etresoft

Level 9

56,662 points

Oct 28, 2008 6:17 AM in response to kznadalin

You test it by running it! First, turn it into a proper Perl script with a shebang line. The shebang isn't really required, but can be useful so that you can run the script without having to type "perl" first.


#!/usr/bin/perl -w
print "What is your last name? ";
$lastname = <STDIN>;
print "What is your first name? ";
$firstname = <STDIN>;
print "Please enter three single digits numbers separated by commas. ";
@numbers= <STDIN>;
print "You entered '@numbers'.";
$firstinitial=index("$firstname", 0, 1);
print "Your user name is '$lastname$firstinitial'. ";
print "Your password is ('@numbers', 2, 1, 0)";

save it is input.pl or something similar.

You can run it by typing "perl input.pl". If you want to get fancy, you can do

chmod +x input.pl

and then run it by just typing "input.pl".

Still, it isn't going to work properly due to:


@numbers= <STDIN>;

When you read from standard input in list context, you read until end-of-file. First, read it into scalar like:


$numbers=<STDIN>;

Then, split it into an array like so:


@numbers=split /,/, $numbers;

Also, don't forget to "use strict" and "chomp" your input. Here is the final version:


#!/usr/bin/perl -w
use strict;
print "What is your last name? ";
my $lastname = <STDIN>;
chomp $lastname;
print "What is your first name? ";
my $firstname = <STDIN>;
chomp $firstname;
print "Please enter three single digits numbers separated by commas. ";
my $numbers= <STDIN>;
chomp $numbers;
my @numbers = split /,/, $numbers;
print "You entered '@numbers'.";
my $firstinitial=index("$firstname", 0, 1);
print "Your user name is '$lastname$firstinitial'. ";
print "Your password is ('@numbers', 2, 1, 0)";

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Answer 2

BobHarris

Level 9

56,933 points

Oct 28, 2008 6:19 AM in response to kznadalin


#!/usr/bin/env perl
print "What is your last name? ";
$lastname = <STDIN>;
chomp($lastname); # remove 
print "What is your first name? ";
$firstname = <STDIN>;
chomp($firstname); # remove 
print "Please enter three single digits numbers separated by commas. ";
#@numbers= <STDIN>; # Perl doesn't know you want to split on commas
$numstr= <STDIN>; # I put 1,2,3 into a string
chomp($numstr); # remove 
@numbers = split(/,/,$numstr); # now I split into an array on the commas
print "You entered '@numbers'.";
#$firstinitial=index("$firstname", 0, 1); # was giving -1
$firstname =~ /^(.)/; # so I used a different trick
$firstinitial = $1; # to get first letter
print "Your user name is '$lastname$firstinitial'. ";
print "Your password is ('@numbers', 2, 1, 0)";

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Answer 3

kznadalin Author

Level 1

0 points

Oct 28, 2008 5:02 PM in response to BobHarris

I forgot to ask, how would I be able to include a foreach to get the user's 3 one-digit numbers to reverse to become the password? Any help is much appreciated.
Thanks,
Karen

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Answer 4

etresoft

Level 9

56,662 points

Oct 29, 2008 5:37 AM in response to kznadalin

reverse @numbers;

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