RtlStringCbVPrintf function

The RtlStringCbVPrintfW and RtlStringCbVPrintfA functions create a byte-counted text string, with formatting that is based on supplied formatting information.


NTSTATUS RtlStringCbVPrintf(
  _Out_ LPTSTR  pszDest,
  _In_  size_t  cbDest,
  _In_  LPCTSTR pszFormat,
  _In_  va_list argList


pszDest [out]

A pointer to a caller-supplied buffer that receives a formatted, null-terminated string. The function creates this string from both the formatting string that is supplied by pszFormat and the arguments supplied by argList.

cbDest [in]

The size of the destination buffer, in bytes. The buffer must be large enough to contain the formatted string plus the terminating null character.

For Unicode strings, the maximum number of bytes is NTSTRSAFE_MAX_CCH * sizeof(WCHAR).

For ANSI strings, the maximum number of bytes is NTSTRSAFE_MAX_CCH * sizeof(char).

pszFormat [in]

A pointer to a null-terminated text string that contains printf-styled formatting directives.

argList [in]

A va_list-typed argument list. Arguments contained in the argument list will be interpreted by using the formatting string that is supplied by pszFormat.

Return value

The function returns one of the NTSTATUS values that are listed in the following table. For information about how to test NTSTATUS values, see Using NTSTATUS Values.

Return codeDescription

This success status means source data was present, the output string was created without truncation, and the resultant destination buffer is null-terminated.


This warning status means the operation did not complete due to insufficient space in the destination buffer. The destination buffer contains a truncated version of the created string.


This error status means the function received an invalid input parameter. For more information, see the following paragraph.

The function returns the STATUS_INVALID_PARAMETER value when:

  • The value in cbDest is larger than the maximum buffer size.
  • The destination buffer was already full.
  • A NULL pointer was present.
  • The destination buffer length was zero, but a nonzero length source string was present.



RtlStringCbVPrintfW and RtlStringCbVPrintfA should be used instead of the following functions:

  • vsprintf

  • vswprintf

  • _vsnprintf

  • _vsnwprintf

All of these functions accept a format string, along with a set of arguments in a va_list-typed argument list, and return a formatted string. The size, in bytes, of the destination buffer is provided to RtlStringCbVPrintfW and RtlStringCbVPrintfA to ensure that they do not write past the end of the buffer.

For more information about va_list-typed argument lists, see the Microsoft Windows SDK documentation.

Use RtlStringCbVPrintfW to handle Unicode strings and RtlStringCbVPrintfA to handle ANSI strings. The form you use depends on your data, as shown in the following table.

String data typeString literalFunction








If pszDest and pszFormat point to overlapping strings or if any argument strings overlap, the behavior of the function is undefined..

Neither pszFormat nor pszDest should be NULL. If you need to handle NULL string pointer values, use RtlStringCbVPrintfEx.

For more information about the safe string functions, see Using Safe String Functions.


Target platform


Available starting with Windows XP with Service Pack 1 (SP1).


Ntstrsafe.h (include Ntstrsafe.h)





Unicode and ANSI names

RtlStringCbVPrintfW (Unicode) and RtlStringCbVPrintfA (ANSI)

See also




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