StringCchGetsEx
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8/27/2008
This function is a replacement for gets.
The size, in characters, of the destination buffer is provided to the function to ensure that StringCchGetsEx does not write past the end of this buffer. It retrieves one line of text from stdin, a newline ('\n') ending the input.
The line of text is copied to the destination buffer, and the carriage return is replaced with a null character.
StringCchGetsEx adds to the functionality of StringCchGets 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.
Note
This function can only be used inline.
Syntax
HRESULT StringCchGetsEx(
LPTSTR pszDest,
size_t cchDest,
LPTSTR *ppszDestEnd,
size_t *pcchRemaining,
DWORD dwFlags
);
Parameters
- pszDest
[out] Pointer to a buffer that receives the copied characters.
cchDest
[in] Size of the destination buffer, in characters.This value must be at least 2 for the function to succeed.
The maximum number of characters allowed, including the terminating null character, is STRSAFE_MAX_CCH.
If cchDest is too small to hold the full line of text, the data is truncated.
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("")).
This flag is useful for emulating functions such as lstrcpy.
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.
Return Value
This function returns an HRESULT, as opposed to gets, which returns a pointer.
It is strongly recommended that you use the SUCCEEDED and FAILED macros to test the return value of this function.
| Value | Description |
|---|---|
S_OK |
Characters were read from stdin, were copied to the buffer at pszDest, and the buffer was null-terminated. |
STRSAFE_E_END_OF_FILE |
Indicates an error or end-of-file condition. To determine which condition occurred, use feof or ferror. |
STRSAFE_E_INVALID_PARAMETER |
The value in cchDest is larger than the maximum allowed value or an invalid flag was passed. |
STRSAFE_E_INSUFFICIENT_BUFFER |
The value in cchDest is 1 or less. |
Remarks
StringCchGetsEx provides additional processing for proper buffer handling in your code.
Poor buffer handling is implicated in many security issues that involve buffer overruns. StringCchGetsEx always null-terminates a nonzero-length destination buffer.
StringCchGetsEx can be used in its generic form, or specifically as StringCchGetsExA (for ANSI strings) or StringCchGetsExW (for Unicode strings). The form to use is determined by your data.
| String data type | String literal | Function |
|---|---|---|
char |
"string" |
StringCchGetsExA |
TCHAR |
TEXT("string") |
StringCchGetsEx |
WCHAR |
L"string" |
StringCchGetsExW |
StringCchGetsEx is not a replacement for fgets. That function does not replace newline characters with a null terminator.
The value of pszDest should not be NULL unless the STRSAFE_IGNORE_NULLS flag is specified.
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 |