Can't use an undefined value as an ARRAY reference

[pnsreee]

Hi all,

Im trying to print ARRAY OF ARRAYS using following code.

for $i (0..10) {
    print "\t [ @{$myvar[$i]} ] ,\n";
}
 

But it is giving following error.

Can't use an undefined value as an ARRAY reference at perl23.plx line 18.

Please help me to solve this problem.

[KevinADC]

do this:

for $i ( 0 .. 10 ) {
   print "$i = $myvar[$i]\n"
   #print "\t [ @{$myvar[$i]} ] ,\n";
}

and see what gets printed. Your code is not necessarily the problem, it's the data, @myvar must not be defined or some elements are not defined.

[pnsreee]

do this:

for $i ( 0 .. 10 ) {
   print "$i = $myvar[$i]\n"
   #print "\t [ @{$myvar[$i]} ] ,\n";
}

and see what gets printed. Your code is not necessarily the problem, it's the data, @myvar must not be defined or some elements are not defined.

Hi kevin,

I tried with ur code but it is giving referances of arrays.

It is like

1 = ARRAY(0x814fd24)
2 = ARRAY(0x816f054)
3 = ARRAY(0x816f0cc)
4 = ARRAY(0x816f144)
5 = ARRAY(0x816f1bc)
6 = ARRAY(0x816f234)
7 = ARRAY(0x816f2ac)
8 = ARRAY(0x816f338)
9 = ARRAY(0x816f3b0)

[KevinADC]

try this then:

for $i ( 0 .. 10 ) {
   print "$i = $myvar[$i]\n"
   print "\t [ @{$myvar[$i]} ] ,\n";
}

and see how far it gets before printing the error message.

[lukertin]

It's his code...

the for loop goes from 0 to 10, but there are only 8 elements in the array, so it is obviously going to run into an error.

for $i (0..$#myvar) {
    print "\t [ @{$myvar[$i]} ] ,\n";
}
 

should fix the problem, since you're only looping through those elements which exist.

[KevinADC]

It's his code...

the for loop goes from 0 to 10, but there are only 8 elements in the array, so it is obviously going to run into an error.

for $i (0..$#myvar) {
    print "\t [ @{$myvar[$i]} ] ,\n";
}
 

should fix the problem, since you're only looping through those elements which exist.

Good observation lukertin.

[StoneSoup]

But doesn't perl just put in null equivalents?

[numberwhun]

But doesn't perl just put in null equivalents?

Sure, if you tell it to when you are defining the elements. But, if you are accessing them and you provide an index that isn't defined, then you will get an error.

lukertin gave a good example of how to set your limit to the number of elements in the array.

Regards,

Jeff

[pietsnot]

Hi,
In case you don't know the size or your array, you can use the "exists" function: http://perldoc.perl.org/functions/exists.html
try something like

for $i (0..10) {
if (exists @{$myvar[$i]})
{
print "\t [ @{$myvar[$i]} ] ,\n";
}
}