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RtlStringCchVPrintf function

The RtlStringCchVPrintfW and RtlStringCchVPrintfA functions create a character-counted text string, with formatting that is based on supplied formatting information.


NTSTATUS RtlStringCchVPrintf(
  _Out_  LPTSTR pszDest,
  _In_   size_t cchDest,
  _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.

cchDest [in]

The size of the destination buffer, in characters. The buffer must be large enough to contain the formatted string plus the terminating null character. The maximum number of characters allowed is NTSTRSAFE_MAX_CCH.

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 cchDest 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.



RtlStringCchVPrintfW and RtlStringCchVPrintfA should be used instead of the following functions:

  • vsprintf

  • vswprintf

  • _vsnprintf

  • _vsnwprintf

All of these functions accept a format string and its arguments, which are provided as a va_list-typed argument list, and return a formatted string. RtlStringCchVPrintfW and RtlStringCchVPrintfA receive the size, in characters, of the destination buffer to ensure that the functions 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 RtlStringCchVPrintfW to handle Unicode strings and RtlStringCchVPrintfA 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 can be NULL. If you need to handle NULL string pointer values, use RtlStringCchVPrintfEx.

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



Available in Windows XP with Service Pack 1 (SP1) and later versions of Windows.


Ntstrsafe.h (include Ntstrsafe.h)





Unicode and ANSI names

RtlStringCchVPrintfW (Unicode) and RtlStringCchVPrintfA (ANSI)

See also




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