AddAtom

The AddAtom function adds a character string to the local atom table and returns a unique value (an atom) identifying the string.

ATOM AddAtom(
  LPCTSTR lpString   // string to add
);

Parameters

lpString

[in] Pointer to the null-terminated string to be added. The string can have a maximum size of 255 bytes. Strings differing only in case are considered identical. The case of the first string added is preserved and returned by the GetAtomName function.

Alternatively, you can use an integer atom that has been converted using the MAKEINTATOM macro. See the Remarks for more information.

Return Values

If the function succeeds, the return value is the newly created atom.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

The AddAtom function stores no more than one copy of a given string in the atom table. If the string is already in the table, the function returns the existing atom and, in the case of a string atom, increments the string's reference count.

If lpString has the form "#1234", AddAtom returns an integer atom whose value is the 16-bit representation of the decimal number specified in the string (0x04D2, in this example). If the decimal value specified is 0x0000 or is greater than or equal to 0xC000, the return value is zero, indicating an error. If lpString was created by the MAKEINTATOM macro, the low-order word must be in the range 0x0001 through 0xBFFF. If the low-order word is not in this range, the function fails.

If lpString has any other form, AddAtom returns a string atom.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Requires Windows 95 or later.
  Header: Declared in Winbase.h; include Windows.h.
  Library: Use Kernel32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT/2000.

See Also

Atoms Overview, Atom Functions, DeleteAtom, FindAtom, GetAtomName, GlobalAddAtom, GlobalDeleteAtom, GlobalFindAtom, GlobalGetAtomName, MAKEINTATOM