C#中，如何获得或设置文件属性（Attributes）

最新推荐文章于 2023-03-23 10:50:49 发布

最新推荐文章于 2023-03-23 10:50:49 发布 · 657 阅读

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#C #C++ #C#

本文介绍了如何使用位运算来正确地检查和设置文件属性。通过对比两种不同的代码实现方式，解释了为何直接比较可能无法准确检测到特定属性（如只读属性），并给出了正确的实现方法。

When testing for a single specific attribute, you need to use bitwise arithmetic. For example,consider the following faulty code:

if(myFile.Attributes==FileAttributes.ReadOnly)

...{...}

This test succeeds only if the read-only attribute is the only attribute for the current file. This israrely the case. If you want to successfully check whether the file is read-only, you need this codeinstead:

if((myFile.Attributes&FileAttributes.ReadOnly)!=0)...{...}

When setting an attribute, you must also use bitwise arithmetic. In this case, you need to ensure
that you don’t inadvertently wipe out the other attributes that are already set.

//Thissetstheread-onlyattribute(andkeepsallothersasis).

myFile.Attributes=myFile.Attributes|FileAttributes.ReadOnly;

//Thisremovestheread-onlyattribute(andkeepsallothersasis).

myFile.Attributes=myFile.Attributes&~FileAttributes.ReadOnly;