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StringCbLengthA function (strsafe.h)

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Determines whether a string exceeds the specified length, in bytes.

StringCbLength is a replacement for the following functions:

Syntax

STRSAFEAPI StringCbLengthA(
  [in]  STRSAFE_PCNZCH psz,
  [in]  size_t         cbMax,
  [out] size_t         *pcbLength
);

Parameters

[in] psz

Type: LPCTSTR

The string whose length is to be checked.

[in] cbMax

Type: size_t

The maximum number of bytes allowed in psz, including those used for the terminating null character. This value cannot exceed STRSAFE_MAX_CCH * sizeof(TCHAR).

[out] pcbLength

Type: size_t*

The number of bytes in psz, excluding those used for the terminating null character. This value is valid only if pcb is not NULL and the function succeeds.

Return value

Type: HRESULT

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
 The string at psz was not NULL, and the length of the string (including the terminating null character) is less than or equal to cbMax characters.
STRSAFE_E_INVALID_PARAMETER
 The value in psz is NULL, cbMax is larger than STRSAFE_MAX_CCH * sizeof(TCHAR), or psz is longer than cbMax.
 

Note that this function returns an HRESULT value, unlike the functions that it replaces.

Remarks

Compared to the functions it replaces, StringCbLength is an additional tool for proper buffer handling in your code. Poor buffer handling is implicated in many security issues that involve buffer overruns.

StringCbLength can be used in its generic form, or in its more specific forms. The data type of the string determines the form of this function that you should use.

String Data Type String Literal Function
char "string" StringCbLengthA
TCHAR TEXT("string") StringCbLength
WCHAR L"string" StringCbLengthW
 

UnalignedStringCbLength is an alias for this function.

Note

The strsafe.h header defines StringCbLength 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 XP with SP2 [desktop apps | UWP apps]
Minimum supported server Windows Server 2003 with SP1 [desktop apps | UWP apps]
Target Platform Windows
Header strsafe.h

See also

StringCchLength