Error in perl: Global symbol requires explicit package name

[Tapas Jha]

Hi,
I am trying to learn perl and before that I have installed perl5.8 in hp-ux 11.0 OS. Here is the
swlist output: perl D.5.8.0.B Perl Programming Language

After perl installation everything is /opt/perl/ directory. Below are the bin,lib,man,html dir.
/opt/perl/bin ;/opt/perl/html;/opt/perl/lib ; /opt/perl/man

Earlier i have perl 4 in my system.I have moved earler perl found in /usr/local/bin and
/usr/contrib/bin to perl4.0.
Now to compile perl program and to get all features of perl program what sort of changes or
configuration do i need to perform?

I am getting below error while compiling one perl program.
""""
Global symbol "%words" requires explicit package name at qsn_ansugng_qw.pl line 6
Global symbol "$name" requires explicit package name at qsn_ansugng_qw.pl line 13
syntax error at qsn_ansugng_qw.pl line 22, near "$words("
Global symbol "$guess" requires explicit package name at qsn_ansugng_qw.pl line 26
Global symbol "$secretword" requires explicit package name at qsn_ansugng_qw.pl line 26
... etc
"""""

Below is my program.
#!/opt/perl/bin/perl -w
use strict;
%words = qw(
fred camel
barney llama
betty alpaca
wilma alpaca
);
print "What is your Name?" ;
$name = ;
chop ($name);
if ( $name eq "Tapas" )
{
print "Hello, $name! How good of you to be here!\n";
}
else
{
print "Hello, $name!\n";
$secretword = $words($name);
print "What is the secret word !";
$guess=;
chop ($guess);
print "Invalid Guess!! Try Again !!!\n";
print "What is the secret word !";
$guess=;
chop ($guess);
}
}

Will appreciate if get proper guidance not only for this but also how to learn perl properly.(Full online help)

Thanx in advance.

Rgds
Tapas

[H.Merijn Brand (procura]

The errors are due to your "use strict;" statements which imposes stricter behaviour on the perl parser.

In perl-4, one has global symbols, and one could give it a temporary value with 'local', which would restore the original value on end of scope.

In perl-5, these type of values still exist, but now that we have modules, we don't want the variables to `leak' to outside a script. Because variables are refered to by name - though namespace hashes - they will not only be visible to the cruel outside world, but they will also be modifiable (changeable, alterable).

In perl-5 we now have lexical variables, only known to the scope in which they are declared, and these do not live in a namespace hash, but in something called a pad.

Lexical vaiables are declared with the keyword 'my':

my $foo = 1;
my @bar = (1, "test", 3.5, sqrt 4);
my %baz = ( green => '#00ff00', red => '#ff0000');

if no scope is active (a block, or a package), the default scope for a variable is the file (script).

--8<---
#!/opt/perl/bin/perl
use strict;
use warnings; # replaces -w, but much better

my %words = (
fred => "camel",
barney => "llama",
betty => "alpaca",
wilma => "alpaca",
);
print "What is your Name?";
chomp (my $name = ); # chomp is a safe chop.
if ($name eq "Tapas") {
print "Hello, $name! How good of you to be here!\n";
}
else {
print "Hello, $name!\n";
my $secretword = $words{$name}; # hashes need braces, no parens
print "What is the secret word !";
chomp ($guess = );
if ($guess ne $secretword) {
print "Invalid Guess!! Try Again !!!\n";
print "What is the secret word !";
chomp ($guess = );
}
}
}
-->8---

# perldoc strict
# perldoc -f chomp
# man perlvar

Enjoy, Have FUN! H.Merijn

[Tapas Jha]

Thanx Procura. Great!!

Now It's working but not accurately. During compling It was giving error "global symbol requires" and i have changed three lines where chomp was there. Put my eg; chomp (my $guess=);

But this program is not matching name, secretword sequesnce. Instead of if condition if you put while then it should terminate when matches but it's not.

Rgds
Tapas

[H.Merijn Brand (procura · Accepted solution]

Look at the lines where I inserted 'my' in front of the variable.

To loop till a valid answer is given:

my $secretword = $words{$name};
for (;;) {
print "Hello, $name!\n";
print "What is the secret word !";
chomp ($guess = );
$guess eq $secretword and last;
print "Invalid Guess!! Try Again !!!\n";
}

Enjoy, Have FUN! H.Merijn