Append BStr
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Below is the code to append Bstr, but in debug mode it gives error ' ::SysFreeString(dest); ' and in release mode if i dont write ' ::SysFreeString(dest); ' it corrupts heap. What optimization i do. BSTR StringAppend(const BSTR dest,const BSTR src) { long destLen=::SysStringByteLen(dest); long srcLen=::SysStringByteLen(src); BSTR st3 = ::SysAllocStringByteLen(NULL,destLen+srcLen); try { if(st3==NULL) { throw "Insufficient Memory"; } else { wcscpy(st3, dest); wcscat(st3, src); ::SysFreeString(dest);// here it gives error in debug mode } } catch(char * error) { throw error; } return st3; }
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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Why are you freeing
dest? :)If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]CPallini wrote:
Why are you freeing dest?
Because if i do not free, it gives error that heap is violated in release mode and when i traced down it goes in the NULL condition.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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why are you modifying a const input parameter ie deleting :mad:
Press F1 for help or google it. Greetings from Germany
KarstenK wrote:
why are you modifying a const input parameter ie deleting Mad
if i do not free all the memory gets exhausted.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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CPallini wrote:
Why are you freeing dest?
Because if i do not free, it gives error that heap is violated in release mode and when i traced down it goes in the NULL condition.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
Please show us the calling code. :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
Please show us the calling code. :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]Here is my calling code. value variable is of type BSTR BSTR GetNewRow() { value=GetLoggedInUser(); BSTR strComma=::SysAllocString(L","); BSTR strNewLine=::SysAllocString(L"\n"); value=StringAppend(value,strComma); value=StringAppend(value,strCategory); value=StringAppend(value,strComma); value=StringAppend(value,strItemName); value=StringAppend(value,strComma); value=StringAppend(value,strInstallDate); value=StringAppend(value,strComma); value=StringAppend(value,strVersion); value=StringAppend(value,strComma); value=StringAppend(value,strValue1); value=StringAppend(value,strComma); value=StringAppend(value,strValue2); value=StringAppend(value,strComma); value=StringAppend(value,strValue3); value=StringAppend(value,strNewLine); ::SysFreeString(strComma); ::SysFreeString(strNewLine); return value; }
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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KarstenK wrote:
why are you modifying a const input parameter ie deleting Mad
if i do not free all the memory gets exhausted.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
If it had to be released from within the function, why does it come into the function as a
constparameter? Isn't this strikingly flashy, yelling "Hey look! I'm the silliest!"?It is a crappy thing, but it's life -^ Carlo Pallini
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KarstenK wrote:
why are you modifying a const input parameter ie deleting Mad
if i do not free all the memory gets exhausted.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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To free up the strings is correct and necessary, BUT NOT in a subroutine. Make it after the sub routine call. :doh:
Press F1 for help or google it. Greetings from Germany
This my calling code tell me where do i free BSTR GetNewRow() { value=GetLoggedInUser(); BSTR strComma=::SysAllocString(L","); BSTR strNewLine=::SysAllocString(L"\n"); value=StringAppend(value,strComma); value=StringAppend(value,strCategory); value=StringAppend(value,strComma); value=StringAppend(value,strItemName); value=StringAppend(value,strComma); value=StringAppend(value,strInstallDate); value=StringAppend(value,strComma); value=StringAppend(value,strVersion); value=StringAppend(value,strComma); value=StringAppend(value,strValue1); value=StringAppend(value,strComma); value=StringAppend(value,strValue2); value=StringAppend(value,strComma); value=StringAppend(value,strValue3); value=StringAppend(value,strNewLine); ::SysFreeString(strComma); ::SysFreeString(strNewLine); return value; }
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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This my calling code tell me where do i free BSTR GetNewRow() { value=GetLoggedInUser(); BSTR strComma=::SysAllocString(L","); BSTR strNewLine=::SysAllocString(L"\n"); value=StringAppend(value,strComma); value=StringAppend(value,strCategory); value=StringAppend(value,strComma); value=StringAppend(value,strItemName); value=StringAppend(value,strComma); value=StringAppend(value,strInstallDate); value=StringAppend(value,strComma); value=StringAppend(value,strVersion); value=StringAppend(value,strComma); value=StringAppend(value,strValue1); value=StringAppend(value,strComma); value=StringAppend(value,strValue2); value=StringAppend(value,strComma); value=StringAppend(value,strValue3); value=StringAppend(value,strNewLine); ::SysFreeString(strComma); ::SysFreeString(strNewLine); return value; }
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
Mogaambo wrote:
BSTR strComma=::SysAllocString(L","); BSTR strNewLine=::SysAllocString(L"\n");
What about changing
BSTRto_bstr_t? Defined in comutil.h The MSDN link says that, A _bstr_t object encapsulates the BSTR data type. The class manages resource allocation and deallocation through function calls to SysAllocString and SysFreeString and other BSTR APIs when appropriate. The _bstr_t class uses reference counting to avoid excessive overhead. --++++++--- Use the+= operatorof_bstr_tto append characters to the end. ifvalueis also declared as a type of_bstr_tthen code can be re-written as,value += strComma;
value += strNewLine;:thumbsup:
modified on Wednesday, May 13, 2009 5:12 AM
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Here is my calling code. value variable is of type BSTR BSTR GetNewRow() { value=GetLoggedInUser(); BSTR strComma=::SysAllocString(L","); BSTR strNewLine=::SysAllocString(L"\n"); value=StringAppend(value,strComma); value=StringAppend(value,strCategory); value=StringAppend(value,strComma); value=StringAppend(value,strItemName); value=StringAppend(value,strComma); value=StringAppend(value,strInstallDate); value=StringAppend(value,strComma); value=StringAppend(value,strVersion); value=StringAppend(value,strComma); value=StringAppend(value,strValue1); value=StringAppend(value,strComma); value=StringAppend(value,strValue2); value=StringAppend(value,strComma); value=StringAppend(value,strValue3); value=StringAppend(value,strNewLine); ::SysFreeString(strComma); ::SysFreeString(strNewLine); return value; }
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
It looks like the problem is in your bad mixing of char and wchar calls: with the following line
BSTR st3 = ::SysAllocStringByteLen(NULL,destLen+srcLen);
you're allocating
(destLen + srcLen + 1)bytes. while in the following callswcscpy(st3, dest);
wcscat(st3, src);you need,
(destLen + srcLen + 2)bytes. :)If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
This my calling code tell me where do i free BSTR GetNewRow() { value=GetLoggedInUser(); BSTR strComma=::SysAllocString(L","); BSTR strNewLine=::SysAllocString(L"\n"); value=StringAppend(value,strComma); value=StringAppend(value,strCategory); value=StringAppend(value,strComma); value=StringAppend(value,strItemName); value=StringAppend(value,strComma); value=StringAppend(value,strInstallDate); value=StringAppend(value,strComma); value=StringAppend(value,strVersion); value=StringAppend(value,strComma); value=StringAppend(value,strValue1); value=StringAppend(value,strComma); value=StringAppend(value,strValue2); value=StringAppend(value,strComma); value=StringAppend(value,strValue3); value=StringAppend(value,strNewLine); ::SysFreeString(strComma); ::SysFreeString(strNewLine); return value; }
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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Mogaambo wrote:
BSTR strComma=::SysAllocString(L","); BSTR strNewLine=::SysAllocString(L"\n");
What about changing
BSTRto_bstr_t? Defined in comutil.h The MSDN link says that, A _bstr_t object encapsulates the BSTR data type. The class manages resource allocation and deallocation through function calls to SysAllocString and SysFreeString and other BSTR APIs when appropriate. The _bstr_t class uses reference counting to avoid excessive overhead. --++++++--- Use the+= operatorof_bstr_tto append characters to the end. ifvalueis also declared as a type of_bstr_tthen code can be re-written as,value += strComma;
value += strNewLine;:thumbsup:
modified on Wednesday, May 13, 2009 5:12 AM
Thanks to all programming bees in helping me to solve my problems.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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It looks like the problem is in your bad mixing of char and wchar calls: with the following line
BSTR st3 = ::SysAllocStringByteLen(NULL,destLen+srcLen);
you're allocating
(destLen + srcLen + 1)bytes. while in the following callswcscpy(st3, dest);
wcscat(st3, src);you need,
(destLen + srcLen + 2)bytes. :)If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]Thanks working great now . i don't know the +2 funda , actually i am c# developer but my firm wants me to develop project in c++. ::SysFreeString(dest); can i free this in StringAppend function itself or after my function returns.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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Thanks working great now . i don't know the +2 funda , actually i am c# developer but my firm wants me to develop project in c++. ::SysFreeString(dest); can i free this in StringAppend function itself or after my function returns.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
Technically you can do it inside. However you probably should revise your design, for instance using a prototype like the following for your function:
HRESULT StringAppend( BSTR * pdst, const BSTR src);
or, better, using, as suggested, the handy
_bstr_twrapper. :)If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
Technically you can do it inside. However you probably should revise your design, for instance using a prototype like the following for your function:
HRESULT StringAppend( BSTR * pdst, const BSTR src);
or, better, using, as suggested, the handy
_bstr_twrapper. :)If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]1. BSTR * pdst why pointer here. BSTR is itself a pointer. 2. What code you have write for StringAppend function ? I want to take some idea from you.It would be very helpful for me.It's a humble request from a programmer to a professional.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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1. BSTR * pdst why pointer here. BSTR is itself a pointer. 2. What code you have write for StringAppend function ? I want to take some idea from you.It would be very helpful for me.It's a humble request from a programmer to a professional.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
Mogaambo wrote:
1. BSTR * pdst why pointer here. BSTR is itself a pointer.
Because the function will internally change the value of the original pointer, i.e.
pdstis aINOUTparameter (this way you state clearly that the function may alter the originaldststring).Mogaambo wrote:
2. What code you have write for StringAppend function ?
Something like
HRESULT StringAppend(BSTR * pdest, const BSTR src)
{
if (pdest == NULL) return E_FAIL;
long destLen=::SysStringLen(*pdest);
long srcLen=::SysStringLen(src);BSTR tmp = ::SysAllocStringLen(NULL,destLen+srcLen);
if( tmp == NULL) return E_FAIL;
wcscpy(tmp, *pdest);
wcscat(tmp, src);
::SysFreeString(*pdest);pdest = &tmp;
*pdest = tmp;
return S_OK;
}Beware: I didn't check this code (moreover I've used just the very basic
E_FAILfailure return value, a good function should be more informative on failure.If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]modified on Wednesday, May 13, 2009 8:02 AM
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Mogaambo wrote:
1. BSTR * pdst why pointer here. BSTR is itself a pointer.
Because the function will internally change the value of the original pointer, i.e.
pdstis aINOUTparameter (this way you state clearly that the function may alter the originaldststring).Mogaambo wrote:
2. What code you have write for StringAppend function ?
Something like
HRESULT StringAppend(BSTR * pdest, const BSTR src)
{
if (pdest == NULL) return E_FAIL;
long destLen=::SysStringLen(*pdest);
long srcLen=::SysStringLen(src);BSTR tmp = ::SysAllocStringLen(NULL,destLen+srcLen);
if( tmp == NULL) return E_FAIL;
wcscpy(tmp, *pdest);
wcscat(tmp, src);
::SysFreeString(*pdest);pdest = &tmp;
*pdest = tmp;
return S_OK;
}Beware: I didn't check this code (moreover I've used just the very basic
E_FAILfailure return value, a good function should be more informative on failure.If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles]modified on Wednesday, May 13, 2009 8:02 AM
BSTR tmp = ::SysAllocStringLen(NULL,destLen+srcLen); dude you haven't added +2 bytes, it is crashing as that of mine, but when i added +2 it is running fine, so whenever i want allocate BSTR do i have 2 add + bytes. BSTR tmp = ::SysAllocStringLen(NULL,destLen+srcLen+2);
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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this is very lame code. You better make at first the output string with CString (or otherwise) and at last ::SysAllocString() :rolleyes:
Press F1 for help or google it. Greetings from Germany
What code you have written if you have to append the BSTR. It's a humble request from programmer to professional.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
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BSTR tmp = ::SysAllocStringLen(NULL,destLen+srcLen); dude you haven't added +2 bytes, it is crashing as that of mine, but when i added +2 it is running fine, so whenever i want allocate BSTR do i have 2 add + bytes. BSTR tmp = ::SysAllocStringLen(NULL,destLen+srcLen+2);
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
Mogaambo wrote:
dude you haven't added +2 bytes
I know, I don't need to (I'm using
SysAllocStringLen, notSysAllocStringByteLen).Mogaambo wrote:
it is crashing as that of mine, but when i added +2 it is running fine
This is very strange.
Mogaambo wrote:
so whenever i want allocate BSTR do i have 2 add + bytes
Nope. Even if your point about the crash is true (and is true, I know) this is a wrong conclusion. :)
If the Lord God Almighty had consulted me before embarking upon the Creation, I would have recommended something simpler. -- Alfonso the Wise, 13th Century King of Castile.
This is going on my arrogant assumptions. You may have a superb reason why I'm completely wrong. -- Iain Clarke
[My articles] -
What code you have written if you have to append the BSTR. It's a humble request from programmer to professional.
“You will never be a leader unless you first learn to follow and be led.” –Tiorio "Coming together is a beginning, staying together is progress, and working together is success." Henry Ford
