RtlUnicodeToMultiByteN function (ntifs.h)

Article
10/21/2021

The RtlUnicodeToMultiByteN routine translates the specified Unicode string into a new character string, using the current system ANSI code page (ACP). The translated string is not necessarily from a multibyte character set.

Syntax

NTSYSAPI NTSTATUS RtlUnicodeToMultiByteN(
  [out]           PCHAR  MultiByteString,
  [in]            ULONG  MaxBytesInMultiByteString,
  [out, optional] PULONG BytesInMultiByteString,
  [in]            PCWCH  UnicodeString,
  [in]            ULONG  BytesInUnicodeString
);

Parameters

[out] MultiByteString

Pointer to a caller-allocated buffer to receive the translated string. MultiByteString buffer must not overlap with UnicodeString buffer.

[in] MaxBytesInMultiByteString

Maximum number of bytes to be written to MultiByteString. If this value causes the translated string to be truncated, RtlUnicodeToMultiByteN does not return an error status.

[out, optional] BytesInMultiByteString

Pointer to a caller-allocated variable that receives the length, in bytes, of the translated string. This parameter is optional and can be NULL.

[in] UnicodeString

Pointer to the Unicode source string to be translated.

[in] BytesInUnicodeString

Size, in bytes, of the string at UnicodeString.

Return value

RtlUnicodeToMultiByteN returns STATUS_SUCCESS.

Remarks

RtlUnicodeToMultiByteN translates the given Unicode string using the current system ANSI code page that was installed at system boot time.

Although BytesInMultiByteString is optional and can be NULL, callers should provide storage for it, because the received length can be used to determine whether the conversion was successful.

This routine does not modify the source string. It returns a null-terminated multibyte string if the given BytesInUnicodeString included a NULL terminator and if the given MaxBytesInMultiByteString did not cause truncation.

Like RtlUnicodeToMultiByteSize, RtlUnicodeToMultiByteN supports only precomposed Unicode characters that are mapped to the current system ANSI code page installed at system boot.

For information about other string-handling routines, see Run-Time Library (RTL) Routines.

Requirements

Requirement	Value
Target Platform	Universal
Header	ntifs.h (include Fltkernel.h, Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	< DISPATCH_LEVEL