[This is preliminary documentation and subject to change.]
The MsiQueryProductState function returns the installed state for a product.
INSTALLSTATE MsiQueryProductState(
LPCTSTR szProduct // product code
);
Windows NT: Requires version 4.0 or later. Available as a redistributable for Windows NT 4.0.
Windows: Requires Windows 95 or later. Available as a redistributable for Windows 95.
Windows CE: Unsupported.
Header: Declared in msi.h.
Import Library: Use msi.lib.
Unicode: Implemented as Unicode and ANSI versions on Windows NT.