Windows API 的 CreateFile() 中 OPEN_ALWAYS 和 CREATE_ALWAYS 的区别 [英] Difference between OPEN_ALWAYS and CREATE_ALWAYS in CreateFile() of Windows API

问题描述

谁能解释一下CreateFile() windows API的函数?

Can anyone explain what the difference is between the creation dispositions OPEN_ALWAYS and CREATE_ALWAYS of the CreateFile() function of the windows API?

对我来说，他们似乎都只是如果文件不存在则创建文件".

To me it seems that they both simply 'create the file if it does not already exist'.

推荐答案

CREATE_ALWAYS 如果文件已经存在，也会截断内容.另一方面，OPEN_ALWAYS 不会破坏已经存在的文件.

CREATE_ALWAYS also truncates the contents if the file already exists. On the other hand, OPEN_ALWAYS will not clobber an already existing file.

以下是表格形式的不同值的工作原理:

Here's how the different values work in tabular form:

                         |                    When the file...
This argument:           |             Exists            Does not exist
-------------------------+------------------------------------------------------
CREATE_ALWAYS            |            Truncates             Creates
CREATE_NEW         +-----------+        Fails               Creates
OPEN_ALWAYS     ===| does this |===>    Opens               Creates
OPEN_EXISTING      +-----------+        Opens                Fails
TRUNCATE_EXISTING        |            Truncates              Fails

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