各种搜索路径问题

python中import一个模块时python解释器的搜索目录顺序：

参考python帮助文档

The
Module Search Path

When a
module named spam is imported, the interpreter
first searches for a built-in module with that name. If not found, it then
searches for a file named spam.py in a list of directories
given by the variablesys.path. sys.path is initialized
from these locations:

• the
  directory containing the input script (or the current directory).

• PYTHONPATH (a list of directory names,
  with the same syntax as the shell variable PATH).


• the
  installation-dependent default.

After
initialization, Python programs can modify sys.path. The directory
containing the script being run is placed at the beginning of the search path,
ahead of the standard library path. This means that scripts in that directory
will be loaded instead of modules of the same name in the library directory.
This is an error unless the replacement is intended. See
section Standard Modules for
more information.

这里也有一篇: Understanding
imports and PYTHONPATH

环境变量

PATH是告诉操作系统到哪些目录里找可执行文件

PYTHONPATH是告诉python解释器到哪些目录去找要加载的模块

Windows找DLL的顺序

With
both implicit and explicit linking, Windows first searches for "known DLLs",
such as Kernel32.dll and User32.dll. Windows then searches for the DLLs in the
following sequence:

The
directory where the executable module for the current process is located.

• The current directory.


• The
  Windows system directory.
  The GetSystemDirectory function retrieves the path
  of this directory.


• The
  Windows directory. The GetWindowsDirectory function
  retrieves the path of this directory.


• The
  directories listed in the PATH environment variable.

参考:msdn

各种搜索路径问题,布布扣,bubuko.com