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Core Modules

“Since the functions in the C runtime library are not part of the Win32 API, we believe the number of applications that will be affected by this bug to be very limited”

Microsoft, January 1999


Python’s standard library covers a wide range of modules. Everything from modules that are as much a part of the Python language as the types and statements defined by the language specification, to obscure modules that are probably useful only to a small number of programs.

This section describes a number of fundamental standard library modules. Any larger Python program is likely to use most of these modules, either directly or indirectly.

Built-in Functions and Exceptions

Two modules are even more basic than all other modules combined: the __builtin__ module defines built-in functions (like len, int, and range), and the exceptions module defines all built-in exceptions.

Python imports both modules when it starts up, and makes their content available for all programs.

Operating System Interface Modules

There are a number of modules providing platform-independent interfaces to the underlying operating system. They are modeled after the POSIX standard API and the standard C library.

The modules in this group include os, which provides file and process operations, os.path which offers a platform-independent way to pull apart and put together file names, and time which provides functions to work with dates and times.

To some extent, networking and thread support modules could also belong in this group, but they are not supported by all Python implementations.

Type Support Modules

Several built-in types have support modules in the standard library. The string module implements commonly used string operations, the math module provides math operations and constants, and the cmath module does the same for complex numbers.

Regular Expressions

The re module provides regular expressions support for Python. Regular expressions are string patterns written in a special syntax, which can be used to match strings, and extract substrings.

Language Support Modules

sys gives you access to various interpreter variables, such as the module search path, and the interpreter version. operator provides functional equivalents to many built-in operators. copy allows you to copy objects. And finally, gc gives you more control over the garbage collector facilities in Python 2.0.

The __builtin__ module

The exceptions module

The os module

The os.path module

The stat module

The string module

The re module

The math module

The cmath module

The operator module

The copy module

The sys module

The atexit module

The time module

The types module

The gc module