strict

[snowrider]

fellow monks, i am currently tring to learn perl so im attempting to do the exercises from the tutorials. here is the code.

#!/opt/perl5/bin/perl -w

use strict;

while($line=<> and $line ne ".\n"){
    push @lines,$line;
}
foreach(reverse @lines){ 
       print;                 
}

for reasons unknow to me i keep getting these errors

Global symbol "$line" requires explicit package name at day1_test.1.pl
+ line 5.
Global symbol "$line" requires explicit package name at day1_test.1.pl
+ line 5.
Global symbol "@lines" requires explicit package name at day1_test.1.p
+l line 6.
Global symbol "$line" requires explicit package name at day1_test.1.pl
+ line 6.
Global symbol "@lines" requires explicit package name at day1_test.1.p
+l line 8.
Execution of day1_test.1.pl aborted due to compilation errors.

does anyone know why this program will not work correctly snowrider

[arturo]

That's because you're not declaring your variables, as strict forces you to do.

You need to add:

my $line;
my @lines;

BEFORE you try to set them, for your code to work. Alternately, omit the FIRST of the declarations above and change that one line to while (my $line = <> ...)

Philosophy can be made out of anything. Or less -- Jerry A. Fodor

[snowrider]

i can make the program work when i use

my $line;
my @lines;

but i cant seem to make

#!/opt/perl5/bin/perl -w

use strict;

#my $line;
my @lines;

while(my $line=<> and $line ne ".\n"){
    push @lines,$line;
}
foreach(reverse @lines){ 
       print;                 
}

work am i doing something wrong?? i keep getting this error

Global symbol "$line" requires explicit package name at day1_test.1.pl
+ line 8.
Value of <HANDLE> construct can be "0"; test with defined() at day1_te
+st.1.pl line 8.
Execution of day1_test.1.pl aborted due to compilation errors.

snowrider

[arturo]

Whoops. The problem is that the second way I gave you won't work because the my $line part of it will fail -- and the variable won't be declared -- if you read in a blank line from the file you're looking through. So you could get a loop with the same logic by changing it to:

while (my $line = <> ) {
    push @lines, $line unless $line eq ".\n";
}

HTH

Philosophy can be made out of anything. Or less -- Jerry A. Fodor

[athomason]

It's great you're using use strict and have warnings enabled; otherwise perl would never warn you about errors like this. The problem you're encountering is that when strict is enabled, perl requires that you declare your variables ($line and @lines, here) before using them. The simplest way is with the my keyword. Check out that link for more info. Other ways to declare variables include use vars and local, though my is the usual method for situations like yours. A quick fix might go like this:

#!/opt/perl5/bin/perl -w

use strict;

my ($line, @lines);

while($line=<> and $line ne ".\n"){
    push @lines,$line;
}
foreach(reverse @lines){ 
       print;                 
}

[snowrider]

thanks for your help you just taught me that i can declare multiple variables at once. and that when you use strict you MUST declare your variables snowrider

[isotope]

If you want it to be a lot cleaner, try:

#!/opt/perl5/bin/perl -w

use strict;

my @lines =();

for(<>) {
  push(@lines);
}
for(reverse(@lines)) {
  print;
}

Or maybe that last for loop can look like:

while(@lines) {
  print pop(@lines);
}



--isotope
http://www.skylab.org/~isotope/

[dsb]

When you 'use strict' you have to declare your variables with 'my'.

use strict;

my $foo;     # declared correctly
my @bar;     # declared correctly
my $foobar = "declared correctly";

- kel -

[snowrider]

thanks alot kel snowrider