StringCbCat function

Concatenates one string to another string. The size of the destination buffer is provided to the function to ensure that it does not write past the end of this buffer.

StringCbCat is a replacement for the following functions:

Syntax

C++
Copy 

HRESULT StringCbCat(
  _Inout_ LPTSTR  pszDest,
  _In_    size_t  cbDest,
  _In_    LPCTSTR pszSrc
);

Parameters

pszDest [in, out]

Type: LPTSTR

The string to which pszSrc is to be concatenated, and that will receive the entire resultant string. The string at pszSrc is added to the end of the string at pszDest.

cbDest [in]

Type: size_t

The size of the destination buffer, in bytes. This value must consider the length of pszSrc plus the length of pszDest plus the terminating null character. The maximum number of bytes allowed is STRSAFE_MAX_CCH * sizeof(TCHAR).

pszSrc [in]

Type: LPCTSTR

The source string that is to be concatenated to the end of pszDest. This string must be null-terminated.

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 codeDescription
S_OK

Source data was present, the strings were fully concatenated without truncation, and the resultant destination buffer is null-terminated.

STRSAFE_E_INVALID_PARAMETER

The value in cbDest is either less than sizeof(TCHAR) or larger than the maximum allowed value.

STRSAFE_E_INSUFFICIENT_BUFFER

The concatenation operation failed due to insufficient buffer space. The destination buffer contains 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.

 

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

Remarks

StringCbCat provides additional processing for proper buffer handling in your code. Poor buffer handling is implicated in many security issues that involve buffer overruns. It always null-terminates and never overflows a valid destination buffer, even if the contents of the source string change during the operation.

StringCbCat 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, as shown in the following table.

String Data TypeString LiteralFunction
char"string"StringCbCatA
TCHARTEXT("string")StringCbCat
WCHARL"string"StringCbCatW

 

Behavior is undefined if the strings pointed to by pszSrc and pszDest overlap.

Neither pszSrc nor pszDest should be NULL. See StringCbCatEx if you require the handling of null string pointer values.

Requirements

Minimum supported client

Windows XP with SP2 [desktop apps | Windows Store apps]

Minimum supported server

Windows Server 2003 with SP1 [desktop apps | Windows Store apps]

Header
Strsafe.h

Unicode and ANSI names

StringCbCatW (Unicode) and StringCbCatA (ANSI)

See also

Reference
StringCchCat
StringCbCatEx
StringCbCatN

 

 

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