StringCchVPrintf_lExW function (strsafe.h)

Article
02/09/2023

Writes formatted data to the specified string using a pointer to a list of arguments. The size of the destination buffer is provided to the function to ensure that it does not write past the end of this buffer.

StringCchVPrintf_lEx is similar to StringCchVPrintfEx but includes a parameter for locale information.

Syntax

STRSAFEAPI StringCchVPrintf_lExW(
  [out]           STRSAFE_LPWSTR                                  pszDest,
  [in]            size_t                                          cchDest,
  [out]           STRSAFE_LPWSTR                                  *ppszDestEnd,
  [out, optional] size_t                                          *pcchRemaining,
  [in]            DWORD                                           dwFlags,
  [in]            _Printf_format_string_params_(2)STRSAFE_LPCWSTR pszFormat,
  [in]            _locale_t                                       locale,
  [in]            va_list                                         argList
);

Parameters

[out] pszDest

The destination buffer, which receives the formatted, null-terminated string created from pszFormat and argList.

[in] cchDest

The size of the destination buffer, in characters. This value must be sufficiently large to accommodate the final formatted string plus 1 to account for the terminating null character. The maximum number of characters allowed is STRSAFE_MAX_CCH.

[out] ppszDestEnd

The address of a pointer to the end of pszDest. If ppszDestEnd is non-NULL and any data is copied into the destination buffer, this points to the terminating null character at the end of the string.

[out, optional] pcchRemaining

The number of unused characters in pszDest, including the terminating null character. If pcchRemaining is NULL, the count is not kept or returned.

[in] dwFlags

One or more of the following values.

Value	Meaning
STRSAFE_FILL_BEHIND_NULL 0x00000200	If the function succeeds, the low byte of dwFlags (0) is used to fill the uninitialized portion of pszDest following the terminating null character.
STRSAFE_IGNORE_NULLS 0x00000100	Treat NULL string pointers like empty strings (TEXT("")).
STRSAFE_FILL_ON_FAILURE 0x00000400	If the function fails, the low byte of dwFlags (0) is used to fill the entire pszDest buffer, and the buffer is null-terminated. In the case of a STRSAFE_E_INSUFFICIENT_BUFFER failure, any truncated string returned is overwritten.
STRSAFE_NULL_ON_FAILURE 0x00000800	If the function fails, pszDest is set to an empty string (TEXT("")). In the case of a STRSAFE_E_INSUFFICIENT_BUFFER failure, any truncated string is overwritten.
STRSAFE_NO_TRUNCATION 0x00001000	As in the case of STRSAFE_NULL_ON_FAILURE, if the function fails, pszDest is set to an empty string (TEXT("")). In the case of a STRSAFE_E_INSUFFICIENT_BUFFER failure, any truncated string is overwritten.

[in] pszFormat

The format string. This string must be null-terminated. For more information, see Format Specification Syntax.

[in] locale

The locale object. For more information, see _create_locale.

[in] argList

The arguments to be inserted into the pszFormat string.

Return value

This function can return one of the following values. It is strongly recommended that you use the SUCCEEDED and FAILED macros to test the return value of this function.

Return code	Description
S_OK	There was sufficient space for the result to be copied to pszDest without truncation and the buffer is null-terminated.
STRSAFE_E_INVALID_PARAMETER	The value in cchDest is either 0 or larger than STRSAFE_MAX_CCH, or the destination buffer is already full.
STRSAFE_E_INSUFFICIENT_BUFFER	The copy operation failed due to insufficient buffer space. Depending on the value of dwFlags, the destination buffer may contain a truncated, null-terminated version of the intended result. In situations where truncation is acceptable, this may not necessarily be seen as a failure condition.

Remarks

For more information on va_lists, see the conventions defined in Stdarg.h.

Behavior is undefined if the strings pointed to by pszDest, pszFormat, or any argument strings overlap.

Neither pszFormat nor pszDest should be NULL unless the STRSAFE_IGNORE_NULLS flag is specified, in which case both may be NULL. However, an error due to insufficient space may still be returned even though NULL values are ignored.

In order to use this function, you must define the following macro in your header file, before including StrSafe.h.

#define STRSAFE_LOCALE_FUNCTIONS

Note

The strsafe.h header defines StringCchVPrintf_lEx as an alias that automatically selects the ANSI or Unicode version of this function based on the definition of the UNICODE preprocessor constant. Mixing usage of the encoding-neutral alias with code that is not encoding-neutral can lead to mismatches that result in compilation or runtime errors. For more information, see Conventions for Function Prototypes.

Requirements

Requirement	Value
Minimum supported client	Windows Vista [desktop apps \| UWP apps]
Minimum supported server	Windows Server 2008 [desktop apps \| UWP apps]
Target Platform	Windows
Header	strsafe.h

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