AddAtom function

Adds a character string to the local atom table and returns a unique value (an atom) identifying the string.

Syntax

ATOM WINAPI AddAtom(
  _In_ LPCTSTR lpString
);

Parameters

lpString [in]

Type: LPCTSTR

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 value

Type: ATOM

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

See also

Reference

DeleteAtom

FindAtom

GetAtomName

GlobalAddAtom

GlobalDeleteAtom

GlobalFindAtom

GlobalGetAtomName

MAKEINTATOM