Login to the screen and file

Question

What design pattern can be used for logging? What is commonly used in this type of situation? Any good tutorials?

I am writing a client-server application using C89 and gcc 4.4.4. Now I need to implement some logging function that will display the log messages on the screen, as well as write to a file.

However, I do not want to display all the log messages (warning, error, critical, fatal, debugging, etc.). Perhaps I can set it to display only errors and nothing more. For example, the user may not be interested in debug messages on the screen.

Answer 1

Some tips / concepts:

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• timestamping.
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• vsnprintf() - , .

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Answer 2

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, : http://blogs.msdn.com/b/dustin_andrews/archive/2007/11/01/how-to-easily-use-the-observer-pattern-to-loosely-couple-tests-to-the-logging-engine.aspx