On 2-Feb-05, at 1:09 PM, Wagner, David --- Senior Programmer Analyst
--- WGO wrote:
> Kevin Horton wrote:
>> I'm a perl newbie working on a script to log data from a device that
>> sends more variables than I need to log. I have a working prototype
>> script, with the list of variables to be logged hard-coded, which
>> means I need to edit the script any time I need to change the items
>> to be printed.
>>
>> Now I want to extend the script to use a configuration file to define
>> the list of variables to be logged, and the order to write them to the
>> log file. I've been messing around with this for many hours, and I've
>> dug through the various perl man pages, plus Perl in a Nutshell, and
>> Programming Perl, but I'm not making any progress.
>>
>> My working prototype script with the hard-coded list of variables
>> prints output with the following line:
>>
>> print OUTPUT
>> "$data_time\t$TACH\t$MP\t$FUEL_FLOW\t$QTY\t$CHT1\t$CHT2\t$CHT3\t$CHT4\ >> t$
>> EGT1\t$EGT2\t$EGT3\t$EGT4\t$OILT\t$OILP\t$VOLT\t$OAT\t$UNIT_TEMP\n";
>>
>> I've got a config file that I read to create an array of variable
>> names that should be logged. The first few items in @variable_list
>> are:
>>
>> data_time
>> TACH
>> MP
>> FUEL_FLOW
>>
>> I would greatly appreciate any hints on how I can use the data in
>> @variable_list to print just the variables I want.
>
> Kevin, I would change it to a hash and then either use some type of
> regex against the keys to get what you want to print out or bypass.
>
But, I also need to control the order the variables are printed. I
understood that if you access the keys in a hash the order you get them
is random. I guess I could create a hash with just the variables I
want, with the keys being numbers. I could then pull the variable for
each key in order. But, I still don't understand the syntax I need.
I.e. once I pull a variable name out of the hash, how do I print that
variable? I tried messing around with symbolic references, but I
couldn't get them to work.
Thanks,
Kevin
Then you sort the keys or make the hash a little more dynamic. You could do
something like:
$hash{key1}[0] = 1; # how the data came in
$hash{key1}[1] = 'value of key1';
$hash{key2}[0] = 2;
$hash{key2}[1] = 'value of key2';
#
# Alpha sort on the keys of hash
#
foreach my $MyKey (sort keys %hash) {
# now print or whatever
}
#
# numeric sort off the first element of hash
#
foreach my $MyKey ( sort {$hash{$a}[0] <=> $hash{$a}[0]} keys %hash) {
# prints in numeric order
}
I believe there are even modules which will help keep the order, but
seems like overkill to me.
Wags ;)
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