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array problem - help!

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array problem - help!

 
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  #1
Jun 29th, 2009
Ok, I am about to pull all my hair out. I have written many many perl scripts and have done it all pretty much. All of a sudden, I have hit a real problem, and I DON'T know why!

I am doing a very simple array declaration by reading a text file into an array.
Perl Syntax (Toggle Plain Text) 
  1. open (FILE, $file_var);
  2. my @contents=<FILE>;
  3. close(FILE);

Pretty simple stuff, huh!? I have used this same routine hundreds of times. But for some reason, declaring the array with "my" is resulting in an empty array! If I just declare it with "@contents=<FILE>", it works fine! Why on earth is this happening? I even declared another array using the same format in the same SCRIPT, and it works fine, but this particular array is turning up empty EVERY time!

I hope someone can help me!

Derek
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Re: array problem - help!

 
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  #2
Jun 29th, 2009
- did you actually open the file?
- does the file you actually opened contain any data?
- does another approach to reading the same file yield data?

3 lines out of context, and an information-free story doesn't help.
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Re: array problem - help!

 
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Jun 29th, 2009
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Originally Posted by Salem View Post
- did you actually open the file?
>>Yes, file exists, returns true with "if (-e $file_var)"

- does the file you actually opened contain any data?
>>Yes

- does another approach to reading the same file yield data?
>>If I just declare it with "@contents=<FILE>", it works fine!

3 lines out of context, and an information-free story doesn't help.
>>Not out of context at all...this is "THE SCRIPT".
It's a simple open-file-and-read-contents-into-array script. The file is a TEXT file, there is at LEAST one line of data in the file, and the path to the file is valid. The "problem" is declaring it with "my", and again, I don't understand why, when I have done it thousands of times this exact way before.
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Re: array problem - help!

 
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  #4
Jun 29th, 2009
OK this is getting stupider by the moment.

I set path like so: $path_to_file="path/file.txt";

If the file exists (need to verify that the file exists before continuing), then read the data into the array, otherwise create the file:

Perl Syntax (Toggle Plain Text) 
  1. if (-e $path_to_file)
  2. {
  3. open (FILE, $path_to_file) or die;
  4. my @contents=<FILE>;
  5. close(FILE);
  6. }
  7. else
  8. {
  9. open(FILE, >$path_to_file);
  10. close(FILE);
  11. }

Tada! The array is EMPTY!

However, if i remove the "if exists" check from around the routine to read data into array, it works! Why!?
Last edited by derekn; Jun 29th, 2009 at 2:11 am.
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Re: array problem - help!

 
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  #5
Jun 29th, 2009
Well the 'my' exists inside a { } scope, so I guess it goes out of scope when the block exits.
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Re: array problem - help!

 
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  #6
Jun 29th, 2009
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Originally Posted by Salem View Post
Well the 'my' exists inside a { } scope, so I guess it goes out of scope when the block exits.

Yep, thats probably the reason.

Perl Syntax (Toggle Plain Text) 
  1. my @contents = ();
  2. if (-e $path_to_file)
  3. {
  4. open (FILE, $path_to_file) or die "$!";
  5. @contents=<FILE>;
  6. close(FILE);
  7. }
  8. print "$_\n" for @contents;
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