Case Sensitivity in Atoms

ID: Q38901

The information in this article applies to:

Microsoft Windows Software Development Kit (SDK) versions 3.0, 3.1
Microsoft Win32 Application Programming Interface (API), included with:
- Microsoft Windows NT, versions 3.5, 3.51
- Microsoft Windows versions 95, 4.0

If the same string is added to an atom table twice, but a different case is used, the string is only stored once; only the first one is present.

The "Microsoft Windows 2.0 Software Development Kit Update" for versions 2.03 and 2.1 states that atoms are case insensitive.

This means that when the AddAtom() function is used, the case is ignored when atoms are compared. Therefore, if AddAtom("DIR") is called, and then AddAtom("dir"), the single atom "DIR" (with a reference count of 2) will result. If AddAtom("dir") is called first, the single atom "dir" will result.

Similarly, the other atom-handling functions are case insensitive. For example, calling FindAtom("dIr") will find the atom "dir", "DIR", or "Dir", and so on.

Additional query words: 3.00 3.10 3.50 4.00

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