The CharToOem function translates a string into the OEM-defined character set. (OEM stands for original equipment manufacturer.)
BOOL CharToOem(
  LPCTSTR lpszSrc,  // pointer to string to translate
  LPSTR lpszDst     // pointer to translated string
);
 The return value is always nonzero.
  Windows NT: Requires version 3.1 or later.
  Windows: Requires Windows 95 or later.
  Windows CE: Unsupported.
  Header: Declared in winuser.h.
  Import Library: Use user32.lib.
  Unicode: Implemented as Unicode and ANSI versions on Windows NT.
String Manipulation Overview, String Manipulation Functions, CharToOemBuff, OemToChar, OemToCharBuff