C / C++ / MFC

Re: problem while freeing a link list within a vector structure

20-Jun-11 22:12

Please use the 'code block' button to format properly your code.

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Stefan_Lang21-Jun-11 0:35

Stefan_Lang

21-Jun-11 0:35

You did not dynamically allocate the first member, so you cannot dynamically free it either.

More to the point: when you push_back() a struct object into that vector of yours, the vector will allocate the required memory and copy the struct you passed into that memory location. The vector is thus responsible for the releaese of that storage, not you. Since you didn't allocate the vector on the heap, it will be automatically deallocated when the variable leaves the scope. But if you defined it globally, then you might want to enforce this earlier, by calling

m_StVector.clear()

Re: problem while freeing a link list within a vector structure

Madan Chauhan21-Jun-11 1:07

Madan Chauhan

21-Jun-11 1:07

thanks for the response.
Yes i have declared m_StVector in App class. So i need to clear it.

but even i do m_StVector.clear() then still i see those memory leaks that are due to the first node of the link list...

well I am still stuck how to free those.

Re: problem while freeing a link list within a vector structure

Stefan_Lang21-Jun-11 1:27

Stefan_Lang

21-Jun-11 1:27

I just noticed that of course you need to free the strings within your struct, and that is something your vector will not take care of.

The best way would be to define both a constructor and destructor for your struct, and use new/delete instead of calloc/free. In the destructor you can then just take care of the string:

struct TestStruct {
   TestStruct() : tchTemp(0) {} // constructor initializes string pointer to 0
   ~TestStruct() { delete [] tchTemp; } // destructor frees string if needed
   void set(const TCHAR* stringvalue) {
      delete [] tchTemp; // release previously allocated memory
      if (stringvalue != 0) {
         // create a copy
         tchTemp = new TCHAR[_tcslen(stringvalue)+1];
         _tcscpy(stringvalue, tchTemp);
      }
      else {
         // reset pointer to 0
         tchTemp = 0;
      }
   }
   TCHAR* tchTemp;
};

void test() {
   std::vector<TestStruct> struct_vect;
   // now fill vector and work with it
   // ...
   struct_vect.clear(); // will delete and deconstruct all objects
}

Note that in order to actually deconstruct (i. e. call the constructor of) the TestStruct objects, you must call delete, not free, on any dynamically allocated objects, and thus you must call new to allocate it. Also you must use new to allocate your strings if you want to use delete to free them. I added a set function to simplify the process of assigning this string properly, using new.

Of course, if you don't want to change your struct definition, you can also loop over the element vectory and free() tchTemp from your first nodes manually.

Re: problem while freeing a link list within a vector structure

CPallini21-Jun-11 1:15

Re: problem while freeing a link list within a vector structure

21-Jun-11 1:15

Why are you using your own list, cannot you use the STL one?
Why are you using C allocation functions?
What is wVectorSt?

David Crow21-Jun-11 4:04

David Crow

21-Jun-11 4:04

Madan Chauhan wrote:
All the nodes become free but one that is very first node in the list does not free.

How are you verifying this?

Madan Chauhan wrote:
Please give me some idea...

Just a tad bit of cleanup:

void main( void )
{
    for (int i = 0; i < 2; i++)
    {
        TEST_STRUCT *ptrCurrent;
        TEST_VECTORST wVectorSt = {0};
        wVectorSt.nVal = i + 1;
   
        for (int j = 0; j < 10; j++)
        {
            TEST_STRUCT *ptrTemp = (TEST_STRUCT *) calloc(1, sizeof(TEST_STRUCT));
            _tcscpy_s(ptrTemp->_tchTemp, _countof(ptrTemp->_tchTemp), _T(""));
            ptrTemp->dwTemp = 10 + j;
            ptrTemp->i64Temp = 100 + j;
            ptrTemp->Next = NULL;
  
            if (wVectorSt.m_ListInVector == NULL)
                wVectorSt.m_ListInVector = ptrTemp;
            else
                ptrCurrent->Next = ptrTemp;
  
            ptrCurrent = ptrTemp;
        }
  
        m_StVector.push_back(wVectorSt);
    }
  
    for (unsigned int i = 0; i < m_StVector.size(); i++)
    {
        TEST_STRUCT *ptrList = m_StVector[i].m_ListInVector;
        while (ptrList != NULL)
        {
            TEST_STRUCT *ptrTemp = ptrList;
            ptrList = ptrList->Next;
            free(ptrTemp);
        }
    } 
}

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I am using VC++ coding,Can any one help me?

lucky_122120-Jun-11 21:14

lucky_1221

20-Jun-11 21:14

I have the List o f names(if list type of list is CString),How to sort the list of names.Anybody knows please send me the syntax of the coding.

Thanks&Regards,
Lucky.

Re: I am using VC++ coding,Can any one help me?

CPallini20-Jun-11 22:10

Re: I am using VC++ coding,Can any one help me?

20-Jun-11 22:10

What kind of container holds the CStrings?
If you are using MFC containers, then have a look at Newcomer's "A guide to sorting"[^].

Cool_Dev20-Jun-11 22:18

Cool_Dev

20-Jun-11 22:18

List classes (std::list or MFC CList etc) are temlate classes and can't have a sort function in a general basis. You have to iterate through the elements in list and implement any of the sorting algorithms as you do with noraml arrays. Since you are dealing with CString, you can use the overloaded < and > operators for comaparing string objects in list.

Converting char array to CSting

VCProgrammer20-Jun-11 1:43

VCProgrammer

20-Jun-11 1:43

Hi all,

I want to convert a char array into CString.

i have tried various ways like

char array[620];
CString str(array,620);
It is giving a compiler error.

Can anybody help me with this?

thanks in advance

Re: Converting char array to CSting [modified]

Pete O'Hanlon20-Jun-11 1:54

Pete O'Hanlon

20-Jun-11 1:54

I don't think you need to specify the length in the CString constructor, so you would have

CString str(array);

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Albert Holguin20-Jun-11 4:36

Albert Holguin

20-Jun-11 4:36

Shouldn't have to as long as the array contents is null terminated.

modified on Monday, June 20, 2011 10:43 AM

Pete O'Hanlon20-Jun-11 6:10

Pete O'Hanlon

20-Jun-11 6:10

Good point.

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CPallini20-Jun-11 1:55

20-Jun-11 1:55

Please let we know the error message ('compiler error' is a bit vague). Anyway I guess you are making a UNICODE build hence the ctor CString::CString(const char *, int) is not available. If the character array is zero-terminated (or you can make it zero-terminated and there aren't other '\0' characters inside) then you could use CString::CString(const char *) instead, namely

C++

CString str(array);

[Win32]Add context menu to edit control

Rajesh R Subramanian20-Jun-11 3:54

Rajesh R Subramanian

20-Jun-11 3:54

VCProgrammer wrote:
char array[620];
CString str(array,620);

Why are you writing that piece of code?

If you want the str object to be initialised with the array contents, you just have to say CString str(array);

Also, if you're talking about a compiler error or so, you should provide the exact details so that others don't have to guess what would that be.

"Real men drive manual transmission" - Rajesh.

Member 296547120-Jun-11 1:24

Member 2965471

20-Jun-11 1:24

How can i add a context menu to an edit control?

I try to handle WM_RBUTTONDOWN in the main window, but don't work if the mouse click is on the edit control.

CPallini20-Jun-11 1:58

20-Jun-11 1:58

You have to subclass the Edit Control, see, for instance Create your own controls - the art of subclassing[^].
Smile | :)

వేంకటనారాయణ(venkatmakam)20-Jun-11 2:23

వేంకటనారాయణ(venkatmakam)

20-Jun-11 2:23

Derive a new class from the CEdit and handle the ON_WM_CONTEXTMENU() message.Check this article for referance,
<href="http: www.codeproject.com="" kb="" edit="" cmenuedit.aspx"="">How to modify a CEdit context menu[^]

http://www.mono-project.com/Main_Page

Member 296547120-Jun-11 3:07

Member 2965471

20-Jun-11 3:07

I'm not using MFC.

So i've to call SetWindowSubclass function and set my own EditProc in which handle WM_CONTEXTMENU?