Define global symbol (Error)

Question

I went through a couple of discussions to find the solution but none of them seem to be working in my case.

I have the following piece of code

print ("Choose from the following\n");
print ("op1 op2\n");

my $x = <>;  
chomp($x);     
print ("x is $x");

if ($x eq "op1")
{
my $DirA = "./A";
my $DirB = "./B"; # **I want to use this dirA and dir B below (Tried switch stmts but I 
#**get the same error)**
}

opendir my($dh), "$DirA" or die "Couldn't open dir DirA!";
my @files = readdir $dh;
closedir $dh;
system("rm -rf diffs");
system ("mkdir diffs\n");
foreach my $input (@list) {
.
.
.
}

I get this error: Global symbol "$DirA" requires explicit package name at test_switch.tc

Can someone please help me with the same. My intension is to add options/switches to my script.. Like "test.pl -A", "test.pl -B" for which I started with a case stmt. Please provide inputs on this.

Can you use perl modules? If so, I suggest you consider using [Getopt::Long](http://search.cpan.org/~jv/Getopt-Long-2.39/lib/Getopt/Long.pm). It will make your life a little easier. — David, Apr 10 '13 at 00:17

score 2 · Answer 1 · answered Apr 10 '13 at 00:12

2

Your $DirA and $DirB are not global, they are only defined in the scope of the if statement in which they're declared with a my. In general, from the documentation: "A my declares the listed variables to be local (lexically) to the enclosing block, file, or eval." To use them in any code that follows, you'll have to do something like:

my $DirA;
my $DirB;

if ($x eq "op1") {
  $DirA = "./A";
  $DirB = "./B";
} else {
  $DirA = ...
  $DirB = ...
}

Note the else: you should also do something if $x is not "op1" because as it stands even if the code had run you'd have gotten an error when trying to pass an undefined value to opendir.

answered Apr 10 '13 at 00:12

miorel

1,863
2
14
18

Thanks. Now I am getting this error after adding that if ($x eq "op1"){ my $DirA = "./A"; my $DirB = "./B"; } else{ my $DirA = "./C"; my $DirB = "./D"; } opendir my($dh), "$DirA" or die "Couldn't open dir DirA!"; Use of uninitialized value in string at test_switch.tc line 47, <> line 1. Couldn't open dir DirA! at test_switch.tc line 47, <> line . This is the opendir line – Rancho Apr 10 '13 at 00:30
Don't put `my` inside the `if` and `else`. This will mask the variables with the same name defined outside the block. To make sure things are ok, `print "DirA = $DirA and DirB = $DirB\n"` before the `opendir`. – miorel Apr 10 '13 at 00:45

score 2 · Answer 2 · answered Apr 10 '13 at 00:13

2

Just declare the variables before the if block and they will be accessible thereafter.

my $DirA;
my $DirB;

if ($x eq "op1") {
    $DirA = "./A";
    $DirB = "./B";
}

answered Apr 10 '13 at 00:13

Borodin

126,100
9
70
144

Define global symbol (Error)

2 Answers2