dakin999 wrote:
>
> I have following code which works ok. It does following:
>
> 1. reads data from a input file
> 2. puts the data into seperate variables in a array
This is where you are getting confused. The data should be /either/ in separate
variables /or/ in an array. See below.
> 3. reads from this array and prints out to another file
>
> It works except that it prints the same record 4 times. I can see I
> have missed some thing in my array definition as their are 4 elements
> in array
No. There is only one element in your array - it is a reference to an anonymous
array.
> it is printing 4 times each element and then moving to next
> element till it reaches eof().
>
> while (<input>) #reading a line from file
> # Read the line into a set of variables
> ($1,$2,$3,$4)=split(/,/,$_);
You have a missing open brace here. This code won't compile.
Never use $1, $2 etc. for you own purposes. Anything that doesn't start with a
letter (and even then a couple of those that do) are used by Perl without your
permission and may well be modified without you noticing.
For now, Let's say you meant
my ($aa, $bb, $cc, $dd) = split /,/;
> # Buid an array with these varaibles
> my @array = ([$1, $2, $3, $4]);
You've initialised @array to a single item. That item is [$aa, $bb, $cc, $dd],
which is an anonymous array. It's equivalent to
my @array;
$array[0] = [$aa, $bb, $cc, $dd];
> foreach my $r(@array) {
So this loop is executed one only, with $r equal to [$aa, $bb, $cc, $dd].
> foreach (@$r){
Now @$r is the same as the list ($aa, $bb, $cc, $dd), so within this loop $_
will be set to each of those values in turn. But you never use $_ within it so
the values in @$r are irrelevant - all that matters is that there are four of
them so you will do this four times.
>
> ... print <out> "$1\n";
> print <out> "$2\n";
> print <out> "$3\n";
> print <out> "$4\n";
> print <out> "\n";
And what you try to do is just print each of the four original variables for
each element of @$r, but this is incorrect syntax and again won't compile. What
you mean is
print out "xx\n";
If it was correct it would be the same as writing
foreach ('a' .. 'd') {
print out 1, "\n";
print out 2, "\n";
print out 3, "\n";
print out 4, "\n";
}
can you see that?
I suggest you meant to split into an array in the first place, and write
something like
while (<input>) { # read a line from file
# split the line into an array
my @data = split /,/;
foreach my $r (@data) {
print out "$r\n";
}
}
Please try to post real code that you are having problems with, or we could
spend a long time finding that all you have done is copied it wrongly into your
questions here.
Bed now <yawn>.
HTH,
Rob
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