I do not understand why the variable @data_file keeps the data from the previous call.
The array is not keeping the data, your data file is keeping it. I believe that you are reading the the data from your file into @data_file here: 
    open(DATA, $dac03_location."/".$file) or die "Cannot open the file
+!";

    #Store the text in an array, easier to work with
    while(<DATA>){
        chomp;
        push(@data_file,$_);
    }
    close(DATA);

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In reply to Re: Why does the array not reset each time I call the function? by wrinkles
in thread Why does the array not reset each time I call the function? by tuxy94

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