Writing a null int to variable when reading file

[cam1878]

What is it you are trying to achieve?
Copy a file to another computer over the network


What is the problem you are having?
When using the put command, it attempts to put a null int into the netStream.


Describe what you have tried to solve this problem
I have tried initializing all the integers in the array to zero, but they are overwritten with null when the program reads a null character from the file.

Turing:

var file, net : int var data : flexible array 1 .. 0 of int var count : int := 0 open : file, "file.exe", read, seek, mod loop     exit when eof (file)     count += 1     new data, count             %Initializes each new array element to zero     read : file, data (count)   %Overwrites the initialization end loop close : file for i : 1 .. count     put net, data (i)           %Attemps to put a null int, resulting in an error end for put "DONE"

Please specify what version of Turing you are using
4.0.5

I would like to point out that the following code successfully creates a new file which is identical to the first, by reading the data the same way, but it writes it rather than putting it to the netStream.

Turing:

var file : int var data : flexible array 1 .. 0 of int var count : int := 0 open : file, "file.exe", read, seek, mod loop     exit when eof (file)     count += 1     new data, count     data (count) := 0           %Initializes every new element in the array to zero     read : file, data (count)   %Reads a null character causing an error end loop close : file open : file, "file2.exe", write for i : 1 .. count     write : file, data (i)           %Error appears at some point while sending the file end for put "DONE" close : file

[DemonWasp]

Not sure whether this is your problem, but your put line doesn't have a colon ( : ) indicating that it's supposed to output to the net stream. Instead of saying "put data(i) to net" it's saying "put net, then put data(i)".

[cam1878]

Sorry that was just a typo, I must have hit backspace it by mistake.

[chrisbrown]

I tried doing the same thing a few years ago and ran into the exact same problem. I don't know if it's possible given Turing's limited capabilities, but a workaround would be to test for a null int, and send an alternate, non-null int instead. The problem is, you have to make sure that alternate is not something that might be sent intentionally as actual data.

I vaguely recall hearing rumours of another fix that involved modifying the libraries, but I never saw it in action.

On another note, resizing large arrays is costly and should be minimized. You will get better performance if you replace

Turing:

var data : flexible array 1 .. 0 of int % AND new data, count

with

Turing:

var data : flexible array 1 .. 1 of int % AND if count > upper(data) then     new data, upper(data) * 2 end if

I noticed a 20% speedup for a 3 MB file.

[Tony]

There is indeed a problem with sending NULLs. If both the client and the server code is your own, then you can send encoded data to avoid NULLs and decode it on the receiving end. Keep in mind the overhead of size and complexity in transmission when designing an appropriate scheme.

[cam1878]

That's what I was planning on doing, but I don't know how to check if an integer is indeed null or not without getting an error in the process of checking.