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This article mainly explains "how to use the logging module in Python". The content in the article is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn how to use the logging module in Python.

1. Why use the logging module?

In practical application, the log file is very important, through the log file, we know the details of the program; at the same time, when something goes wrong, we can also quickly locate the problem through the log. When we write the program, we can also use the output information of the logging module to debug the code.

But many people still use the print () function in their programs to output some information, such as:

Print 'Start reading database'records = model.read_recrods () print' # records', recordsprint 'Updating record...' model.update_records (records) print 'done'

In this way, the disadvantage is obvious. When the program is written and run, we have to delete these print () functions and use them in simple programs. When the program is more complex, this method is very inefficient.

If you use the logging module, see the effect

Import logginglogging.basicConfig (level=logging.INFO) logger = logging.getLogger (_ name__) logger.info ('Start reading database') # read database hererecords = {' john': 55, 'tom': 66} logger.debug (' Records:% slots, records) logger.info ('Updating records...') # update records herelogger.info ('Finish updating records')

The running results are as follows:

INFO:__main__:Start reading databaseINFO:__main__:Updating records... INFO:__main__:Finish updating records

You might ask, what's the difference between this and the print () function? The difference is that the logging module can control whether some statements are output by changing level, for example, when we change level to DEBUG level:

Logging.basicConfig (level=logging.DEBUG)

The output is as follows:

INFO:__main__:Start reading database

DEBUG:__main__:Records: {'john': 55,' tom': 66}

INFO:__main__:Updating records...

INFO:__main__:Finish updating records

Introduction of 2.logging module

The logging module is a package that comes with python, so when you use it, you don't have to install it, just import. There are five level, namely debug, mainly to check the information about the running of the program, generally the information that the debugger wants to see; info, the information that we see whether the program executes as expected; warn, which is unexpected, but does not affect the running of the program; error and critical are some more serious problems that will affect the operation of the program. The default leval is warn, so the debug level and info level will not be output to the log. If you want to see this information, you need to make some settings.

3. Basic settin

We mainly call the function basicConfig (* * kwargs*) to set up logging.

The common parameters are as follows:

Level: mainly adjusts the level of logging

Filename: the path to the output log

Filemode: direct write or append write

Format: format of output

By adjusting format, we can output the format we want, such as:

Import logginglogging.basicConfig (format='% (asctime) s -% (message) slots, datefmt='%d-%b-%y% HV% MV% S') logging.warning ('Admin logged out')

The result is:

12-Jul-18 20:53:19-Admin logged out

This is the time set in the format parameter, so when we get the time, we can output a variety of information we want.

Thank you for reading, the above is the content of "how to use the logging module in Python". After the study of this article, I believe you have a deeper understanding of how to use the logging module in Python, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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