trying to understand rationale of unix stream i/o concept Post: 302333217

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Top Forums UNIX for Dummies Questions & Answers trying to understand rationale of unix stream i/o concept Post 302333217 by kaychau on Saturday 11th of July 2009 05:19:32 PM

07-11-2009

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trying to understand rationale of unix stream i/o concept

I am an entry level programmer with no formal training in computer science. I am trying to enhance my conceptual knowledge about operating systems in general.

I have been using the C programming language on Linux systems for some time and have used the traditional unix stream I/O APIs. The introductory material in books and on the web, typically introduce the unix stream I/O model as "basic unix I/O model is a stream of bytes which can be accessed sequentially or randomly". I understand this part, but I am unable to visualize how else would one access the data. Were the I/O models different before the I/O stream model came in to existence? Are there models in current computing paradigm which are different from the stream I/O. I will appreciate if some can help me visualize both the stream I/O model vs other models (if they exist or existed). Pros-Cons will be a great addition too.

In addition, I came across the following statement on the web (I/O System)

"The basic model of the UNIX I/O system is a sequence of bytes that can be accessed either randomly or sequentially. There are no access methods and no control blocks in a typical UNIX user process."

I do not understand the last statement - what are access methods and control blocks in the context of I/O?

Thanks
Kay

kaychau

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fann_set_callback

FANN_SET_CALLBACK(3)							 1						      FANN_SET_CALLBACK(3)

fann_set_callback - Sets the callback function for use during training

SYNOPSIS

       bool fann_set_callback (resource  $ann, collable  $callback)

DESCRIPTION

	Sets the callback function for use during training. It means that it is called from fann_train_on_data(3) or fann_train_on_file(3).

PARAMETERS

	      o $ann
		-Neural network resource.

	      o $callback
		- The supplied callback function takes following parameters:

		     o ann - The neural network resource

		     o train - The train data resource or NULL if called from fann_train_on_file(3)

		     o max_epochs - The maximum number of epochs the training should continue

		     o epochs_between_reports - The number of epochs between calling this function

		     o desired_error   -  The  desired	fann_get_MSE(3)  or  fann_get_bit_fail(3),  depending  on  the	stop  function	chosen	by
		       fann_set_train_stop_function(3)

		     o epochs - The current epoch

	       The callback should return TRUE. If it returns FALSE, the training will terminate.

RETURN VALUES

       Returns TRUE on success, or FALSE otherwise.

SEE ALSO

       fann_train_on_data(3), fann_train_on_file(3).

PHP Documentation Group 												      FANN_SET_CALLBACK(3)