Python Learning Path-module concepts, special variables in modules, OS, SYS modules

Module concept

1 #Note: The custom module name is not the same as the standard module name, and only the custom module will be imported if the same2 #single module and in the same directory:3 #directly with the import module name, called with the module name. Method Name ()4 #nested under Other folders:5 #from xxx import xxx as alias6 ImportExample7 Importlib.commons8  fromLibImportCommons as Lib_commons9  fromSrcImportCommons as Src_commons

Installing third-party modules
1. SOURCE installation: Download the required module source code, unzip, and execute the file in the setup.py (python3 setup.py install)
2. Pip:pip Install requests

Special variables in the module

1 # __name__==__main__ When executing the current file, the special variable name = = Main 2 # __file__     All comments 4# in the relative path 3# __doc__ file     where the current file is located __cached__  Cache location 5#  __package__ The current file in which package, the project does not count

Os

Provides system-level operations

Os.path.abspath (PATH)#returns the absolute path normalized by pathOs.path.split (PATH)#split path into directory and file name two tuples returnedOs.path.dirname (PATH)#returns the directory of path. is actually the first element of Os.path.split (path)Os.path.basename (PATH)#returns the last file name of path. If path ends with a/or \, then a null value is returned. The second element of Os.path.split (path)Os.path.exists (PATH)#Returns true if path exists, false if path does not existOs.path.isabs (PATH)#returns True if path is an absolute pathOs.path.isfile (PATH)#returns True if path is a file that exists. Otherwise returns falseOs.path.isdir (PATH)#returns True if path is a directory that exists. Otherwise returns falseOs.path.join (path1[, path2[, ...])#when multiple paths are combined, the parameters before the first absolute path are ignoredOs.path.getatime (PATH)#returns the last access time of the file or directory to which path is pointingOs.path.getmtime (PATH)#returns the last modified time of the file or directory to which path is pointing

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Sys

Provide interpreter-related actions

SYS.ARGV           # command-line argument list, the first element is the program itself path sys.exit (n)        # exit program, Exit normally (0) Sys.version       # Gets the version information of the Python interpreter sys.maxint        # the largest int value Sys.path           # Returns the search path for the module, using the value of the PYTHONPATH environment variable when initializing sys.platform      # returns the operating system platform name sys.stdout.write ('please:'= sys.stdin.readline () [:-1]

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Python Learning Path-module concepts, special variables in modules, OS, SYS modules