StringCchPrintfEx

Other versions of this page are also available for the following:

• Windows Embedded CE 6.0 R3

8/27/2008

This function is a replacement for sprintf. It accepts a format string and a list of arguments and returns a formatted string.

The size, in characters, of the destination buffer is provided to the function to ensure that StringCchPrintfEx does not write past the end of this buffer.

StringCchPrintfEx adds to the functionality of StringCchPrintf by returning a pointer to the end of the destination string, and by returning the number of characters left unused in that string.

Flags can also be passed to the function for additional control.

Syntax

HRESULT StringCchPrintfEx(      
    LPTSTR pszDest,
    size_t cchDest,
    LPTSTR *ppszDestEnd,
    size_t *pcchRemaining,
    DWORD dwFlags,
    LPCTSTR pszFormat,
     ...  );  

Parameters

• pszDest
  [out] Pointer to a buffer that receives the formatted, null-terminated string created from pszFormat and its arguments.

• cchDest
  [in] 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.

• ppszDestEnd
  [out] Address of a pointer to the end of pszDest.

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

• pcchRemaining
  [out] Pointer to a variable that indicates the number of unused characters in pszDest, including the terminating null character.

  If pcchRemaining is NULL, the count is not kept or returned.

• dwFlags
  [in] One or more of the following values.

  Value	Description
  STRSAFE_FILL_BEHIND_NULL	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	Treat null string pointers like empty strings (TEXT("")).
  STRSAFE_FILL_ON_FAILURE	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	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	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.

• pszFormat
  [in] Pointer to a buffer containing a printf-style format string.

  This string must be null-terminated.

• ...
  [in] Arguments to be inserted into pszFormat.

Return Value

This function returns an HRESULT, as opposed to sprintf, which returns the number of bytes stored in its destination buffer.

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

Value	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 0 or larger than STRSAFE_MAX_CCH, or the destination buffer is full.
STRSAFE_E_INSUFFICIENT_BUFFER	The copy operation failed due to insufficient buffer space. Depending on the value of dwFlags, the destination buffer might contain a truncated, null-terminated version of the intended result. Where truncation is acceptable, this is not necessarily a failure condition.

Remarks

StringCchPrintfEx provides additional processing for proper buffer handling in your code.

Poor buffer handling is implicated in many security issues that involve buffer overruns. StringCchPrintfEx always null-terminates a nonzero-length destination buffer.

StringCchPrintfEx can be used in its generic form, or specifically as StringCchPrintfExA (for ANSI strings) or StringCchPrintfExW (for Unicode strings). The form to use is determined by your data.

String data type	String literal	Function
char	"string"	StringCchPrintfExA
TCHAR	TEXT("string")	StringCchPrintfEx
WCHAR	L"string"	StringCchPrintfExW

StringCchPrintfEx and its ANSI and Unicode variants are replacements for these functions:

• sprintf
• swprintf
• wsprintf
• _snprintf
• _snwprintf

If the strings pointed to by pszDest, pszFormat, or argument strings overlap, behavior is undefined.

Neither pszFormat nor pszDest should be NULL unless the STRSAFE_IGNORE_NULLS flag is specified; in which case both might be NULL.

An error due to insufficient space might still be returned even though null values are ignored.

Requirements

Header	strsafe.h
Windows Embedded CE	Windows CE 5.0 and later

See Also

Reference

StringCbPrintfEx
StringCchPrintf
StringCchVPrintfEx