StringCchCat Function example

StringcCchCat Function:

Operation: Concatenates one striing to another string.

Syntax:  HRESULT StringCchCat(_Inout_ LPTSTR  pszDest,

                            _In_    size_t  cchDest,
                            _In_    LPCTSTR pszSrc
                            );

Arguments: pszDest: Destination buffer to which pszSrc will be concatenated.

           cchDest: cch stands for count of characters. This argument is mainly 

                    provided so that we will not be writing after the end of 

                    buffer  

           pszSrc:  Null terminated string which you want to concatenate.

Header File : #include <strsafe.h>

Return Value:  Type: HRESULT 

               S_OK    If successful

We will see the other return values also

Sample Code1: 

#include "stdafx.h"
#include "stdlib.h"
#include "winerror.h"
#include "windows.h"
#include "strsafe.h"


int _tmain(int argc, _TCHAR* argv[])
{
 TCHAR pszDest[100]= _T("Hello");
 TCHAR pszSrc[100] = _T("World");
 HRESULT hresult;

 hresult = StringCchCat(pszDest, _countof(pszDest), pszSrc);

 if (SUCCEEDED(hresult))
 {
  printf("String Succesfully concatenated:%ls\n", pszDest);
 }
 else
 {
  printf("Concatenation Failed:%d\n", GetLastError());
 }
 return 0;
}

O/P: String Successfully concatenated:HelloWorld

What happens if I passed 0 as the second argument in the StringCchCat function.

Sample Code 2:

#include "stdafx.h"

#include "stdlib.h"

#include "winerror.h"

#include "windows.h"

#include "strsafe.h"

int _tmain(int argc, _TCHAR* argv[])

{

TCHAR pszDest[100]= _T("Hello");

TCHAR pszSrc[100] = _T("World");

HRESULT hresult;

hresult = StringCchCat(pszDest, 0, pszSrc);

if (SUCCEEDED(hresult))

{

printf("String Succesfully concatenated:%ls\n", pszDest);

}

else

{

if (hresult == STRSAFE_E_INVALID_PARAMETER)

printf("Invalid Parameter Passed\n");

else if(hresult == STRSAFE_E_INSUFFICIENT_BUFFER)

printf("Destination Size not sufficient\n");

else

printf("Some unknown error happened\n");

}

return 0;

}

O/P: Invalid Parameter Passed.

So whenever u pass 0 as count you will get STRSAFE_E_INVALID_PARAMETER error

We will also make some more modifications to look what happens when the destination

buffer size is not enough to add all the contents of the source buffer

Sample Code 3:

#include "stdafx.h"
#include "stdlib.h"
#include "winerror.h"
#include "windows.h"
#include "strsafe.h"


int _tmain(int argc, _TCHAR* argv[])
{
 TCHAR pszDest[8]= _T("Hello");
 TCHAR pszSrc[100] = _T("World");
 HRESULT hresult;

 hresult = StringCchCat(pszDest, _countof(pszDest), pszSrc);

 if (SUCCEEDED(hresult))
 {
  printf("String Succesfully concatenated:%ls\n", pszDest);
 }
 else
 {
  if (hresult == STRSAFE_E_INVALID_PARAMETER)
   printf("Invalid Parameter Passed\n");
  else if(hresult == STRSAFE_E_INSUFFICIENT_BUFFER)
   printf("Destination Size not sufficient\n");
  else
   printf("Some unknown error happened\n");
 }
 return 0;
}

O/P: Destination Size not sufficient.

If you want to perform string concatenation on char variables instead of TCHAR you have to

use StringCchCatA(ANSI) function arguments will be same.

If you want to perform string concatenation on WCHAR variables you have to use 

StringCchCatW(Unicode0 function.