Article ID: 108450 - View products that this article applies to.
This article was previously published under Q108450
MultiByteToWideChar() maps a character string to a wide-character string. The declaration of this application programming interface (API) is as follows:
The first parameter, uCodePage, specifies the codepage to be used when performing the conversion. This discussion applies to the first parameter of WideCharToMultiByte() as well. The codepage can be any valid codepage number. It is a good idea to check this number with IsValidCodepage(), even though MultiByteToWideChar() returns an error if an invalid codepage is used. The codepage may also be one of the following values:
CP_ACP instructs the API to use the currently set default Windows ANSI codepage. CP_OEMCP instructs the API to use the currently set default OEM codepage.
If Win32 ANSI APIs are used to get filenames from a Windows NT system, use CP_ACP when converting the string. Windows NT retrieves the name from the physical device and translates the OEM name into Unicode. The Unicode name is translated into ANSI if an ANSI API is called, then it can be translated back into Unicode with MultiByteToWideChar().
If filenames are being retrieved from a file that is OEM encoded, use CP_OEMCP instead.
When an application calls an ANSI function, the FAT/HPFS file systems will call AnsiToOem(); however, if an ANSI character does not exist in an OEM codepage, the filename will not be representable. In these cases, SetFileApisToOEM() should be called to prevent this problem by setting a group of the Win32 APIs to use the OEM codepage instead of the ANSI codepage.