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Has anybody figured out a way to preallocate a multimap?
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Do you mean to allocate it at compile time? Or do you mean that you know how many entries you will add, and you want to reserve the memory ahead of time?
If the former, I don't believe it can be done.
If the latter, I would suggest making the values pointers, e.g.,
map<string, cfoo*="">. You could potentially preallocate the memory for
CFoos (simple if it is just a struct, otherwise more work). The
memory for the nodes would not be preallocated, but the nodes would
be fairly small.
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Well, I was unaware of the following article when I replied earlier. You may be well aware of it. It applies to maps, but I don't know whether multimaps are supported, I have not spent the time to check.
For what it is worth: http://www.codeproject.com/vcpp/stl/PGIL.asp
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I think you'd have to hook in your own allocator for that.
The std::[multi]maps are implemented as red/black binary trees IIRC, so they are very dynamic in structure, just like a linked list. Hence you don't see a reserve() method in their interfaces.
hashmaps are by definition preallocated, but I'm not sure if hashmaps are part of STL yet.
--
Denn du bist, was du isst!
Und ihr wisst, was es ist!
Es ist mein Teil...?
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Hi
I need a little (or big...) help with my Visual C++ 6.0 compiler because I guess I found a C++ programm using some STL functions which my compiler does not understand. Basically it's about the functions from STL called "mem_fun_ref" and "mem_fun".
In short, I do not get the following little program to get compiled:
/* The following code example is taken from the book
* "The C++ Standard Library - A Tutorial and Reference"
* by Nicolai M. Josuttis, Addison-Wesley, 1999
*
* (C) Copyright Nicolai M. Josuttis 1999.
* Permission to copy, use, modify, sell and distribute this software
* is granted provided this copyright notice appears in all copies.
* This software is provided "as is" without express or implied
* warranty, and with no claim as to its suitability for any purpose.
*/
//#define mem_fun1 mem_fun
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>
class Person {
private:
std::string name;
public:
//...
void print () const {
std::cout << name << std::endl;
}
void printWithPrefix (std::string prefix) const {
std::cout << prefix << name << std::endl;
}
};
void foo (const std::vector<Person>& coll)
{
using std::for_each;
using std::bind2nd;
using std::mem_fun_ref;
// call member function print() for each element
for_each (coll.begin(), coll.end(),
mem_fun_ref(&Person::print));
// call member function printWithPrefix() for each element
// - "person: " is passed as an argument to the member function
for_each (coll.begin(), coll.end(),
bind2nd(mem_fun_ref(&Person::printWithPrefix),
"person: "));
}
void ptrfoo (const std::vector<Person*>& coll)
// ^^^ pointer !
{
using std::for_each;
using std::bind2nd;
using std::mem_fun;
// call member function print() for each referred object
for_each (coll.begin(), coll.end(),
mem_fun(&Person::print));
// call member function printWithPrefix() for each referred object
// - "person: " is passed as an argument to the member function
for_each (coll.begin(), coll.end(),
bind2nd(mem_fun(&Person::printWithPrefix),
"person: "));
}
int main()
{
std::vector<Person> coll(5);
foo(coll);
std::vector<Person*> coll2;
coll2.push_back(new Person);
ptrfoo(coll2);
}
Hint: the first compiler error could be ""solved"" by removing the "const" from "void print () const {".
Nevertheless I get the following errors:
E:\myProjects\memfun1\memfun1.cpp(45) : error C2784: 'class std::mem_fun_ref_t<_R,_Ty> __cdecl std::mem_fun_ref(_R (__thiscall _Ty::*)(void))' : could not deduce template argument for '<Unknown>' from 'void (__thiscall Person::*)(class std::basic_st
ring<char,struct std::char_traits<char>,class std::allocator<char> >) const'
E:\myProjects\memfun1\memfun1.cpp(64) : error C2784: 'class std::mem_fun_t<_R,_Ty> __cdecl std::mem_fun(_R (__thiscall _Ty::*)(void))' : could not deduce template argument for '<Unknown>' from 'void (__thiscall Person::*)(class std::basic_string<cha
r,struct std::char_traits<char>,class std::allocator<char> >) const'
The g++ compiler under Linux simply compiles it without problems...
Any help very welcome!
Bye,
T.T.H.
---------------------------------------------
UPDATE:
I hate it when that happens: I search the net for one hour then post the question here and 5 seconds afterwards I find the answer myself...
http://www.gamedev.net/community/forums/topic.asp?topic_id=187903&forum_id=21
So basically it's a problem with the STL implementation of VC6.0.
T.T.H.
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It compiles on VC 7.1.
Kevin
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HI,
I've created an ATL Composite control using ATL COM AppWizard in VC++ 6.0.
I want to print the control from the container application like word.
How to add support for printing this control.
The dialog has buttons and edit boxes and list control.
I tried sending the WM_PAINT message in OnDraw() for each of the controls within the dialog. It just paints the view of list control. Other controls are not rendered.
Your help will be higly appreciated.
Thanks,
Veena
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I am using few classes which r derived from MFC, CMap class. When i include these files in my ATL project which is simple DLL project, i get the following error:
----------------------------------------------------------------------
mfcs42d.lib(dllmodul.obj) : error LNK2005: _DllMain@12 already defined in MyProject.obj
mfcs42d.lib(dllmodul.obj) : warning LNK4006: _DllMain@12 already defined in MyProject.obj; second definition ignored
----------------------------------------------------------------------
Can anybody suggest how i can avoid these error and wht is the reason for such an error.
ksd
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As I understand it, MFC does not mix too well with ATL. I've read that it's OK to use ATL in MFC but not so good the other way round. Though in VC7 there are now a number of shared classes. Plus ATL has its own collection classes. If you're using VC7 why not investigate CAtlMap? If you're using VC6 try STL map. Of course this may not be feasible if, as it seems, you have a lot of old code that uses CMap.
Kevin
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If you are using VC7 you can check "Support for MFC" when you create a new ATL project. Unfortunately I don't really know what it does, so I can't help you changing the settings on your current project.
--
Denn du bist, was du isst!
Und ihr wisst, was es ist!
Es ist mein Teil...?
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I was once asked to look at why a process was taking a long time to accomplish a task. One thing the process did was load a large number of entries into a CMap.
I did a bit of experimentation, and found that inserting 300,000 entries into a CMap took a bit over 4 hours. Doing 300,000 lookups on the CMap also took a bit over 4 hours.
I tried an STL map, and found that inserting 300,000 entries took 22 seconds, and looking up 300,000 entries took 19 seconds.
I've never had any use for CMaps. If you can, you might try switching to an STL map.
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Wow! That's a huge difference! Nowadays I go for STL first with new MFC code. Not that I get to do much new MFC code these days. Though sometimes, depending on the context, the MFC stuff can be more convenient, e.g., CString.
Kevin
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I have a modeless dialog with no Edit controls on it. The dialog is created by the WTL wizard. I would like to trap WM_CHAR messages at the dialog level. In the message map for the dialog I have added code like this:
MESSAGE_HANDLER(WM_KEYDOWN, OnKeyDown)
MESSAGE_HANDLER(WM_KEYUP, OnKeyUp)
MESSAGE_HANDLER(WM_CHAR, OnChar)
but no one of the methods gets called when pressing keys on the keyboard.
Any suggestion?
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Sorry if it's wrong forum but there isn't one for OLEDB... Anyway. Is OLEDB simultaneous-multithread-access safe? Also ... using OLEDB - if different threads need to access the same database is it better to open that database from each thread or is it OK to use the same opened database object from different threads at the same time - reuse the connection?
Sorry for such a basic question. 
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AFAIK OLEDB is thread safe.
Good luck
-pete
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Hi all,
I want to develope ATL Container (in which i can host other activex control). How do i proceed, App Wizard does not help more to develope the ATL Container.
Please show me the right direction...........
I will realy appriciate any help !
Thank you,
Vishal More
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Take a look at CAxWindow.
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I have created Composite Control and I have placed a Slider Control on that Composite Control( i.e The dialog...) Now my problem is
I get the Edge(the dotted rectangle on that slider control) So how do i remove those edge or dotted rectangle
I am using
VC++ 6.0
ATL wizard for creating composite control
regards
Balkrishna Talele
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How to add toolbar to WTL Dialogbased Application? Pl give Example.
Thanks in advance
satya
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I want to provide exclusively only Drag ability to my CListViewCtrl, which is displaying the list of File names using SHGetFileInfo.
I mean am showing list of files located in a specific folder using CListViewCtrl.I am getting the details of files using HGetFileInfo.
Now,i should be able to drag the selected file form CListViewCtrl to windows explorer(into any folder/desktop).
RAGU MANDA
(MALAYSIA)
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actualy i have MDI app w/out doc/view arch.
so i create views on DialogImpl base
class CSearchView :
public CDialogImpl<csearchview>,
public CDialogResize<csearchview>,
public CWinDataExchange<csearchview>
---
Questions is,- how to create CMultiPaneStatusBarCtrl
on dialog. & also i need auto-resize it with
CDialogResize.
also there is one problem what CDialogResize does not accepts CStatusBar because it is not a window!
atlwin.h & atlctrls.h asserts on ::IsWindow(m_hWnd)
so how-to ?
----------------------------
never stop coding.
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Hi,
How to change/set text color in RichEditCtrl/CRichEditCtrlView ???
I'm using WTL.
thanks
Bandu
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I have writtern a COM Service, and i am using LPSAFEARRAY and LPSAFEARRAY * in inteface methods.
When i try to create the com on a remote machine it did not create..
but when i try to create on local machine it creates but i am unable to call any methods it gives me error "Bad Variable Type"
Can anyone help...
Humair Syed
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"LPSAFEARRAY" and "LPSAFEARRAY*" can be used only inside C++ sources, but not in IDL files. The valid IDL syntax for "LPSAFEARRAY" is SAFEARRAY(some_simple_type). For example:
[] HRESULT Test1([in] SAFEARRAY(BSTR) StringsNotApplicableForVB)<br />
[] HRESULT Test2([in] SAFEARRAY(BSTR) *Strings)<br />
[] HRESULT Test3([in,out] SAFEARRAY(BSTR) *Strings)<br />
[] HRESULT Test4([out,retval] SAFEARRAY(BSTR) *Strings)
With best wishes,
Vita
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In Visual basic, we can use TypeName to get the name of a COM object.
How can I do that in VC?
Some people told me that I should try ITypeInfo, but I can't find anything useful in it.
Thanks.
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