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leon de boer wrote: Sometimes I just shake my head at answers offered
I get much the same feeling with more and more of the questions posted here.
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1.dev enviroment：VC++ 6.0
2.build program in 'release'
3.store 1000000 simple objects in CArray
4.run the program without debug
After running the code , it's about 85M memory cannot be release on my computer.
Can anyone explain and solve the problem for me? Thanks.
BTW：Because of the legency project code,my dev IDE is not allowed to update to the latest VisualStudio. So i have to solve the problem in VC 6.0 IDE.
#include "afxtempl.h"
long int g_cCount = 0;
long int g_dCount = 0;
class CMyTest
{
public:
CString m_str;
CMyTest()
{
m_str = "test string";
g_cCount++;
}
~CMyTest()
{
g_dCount++;
}
};
typedef CArray<CMyTest,CMyTest&> CArrayTest;
void Test()
{
g_cCount = 0;
g_dCount = 0;
CArrayTest testArray;
int count = 1000000;
for(int i =0;i < count; i++ )
{
CMyTest testObj;
testObj.m_str = "test string";
testArray.Add(testObj);
}
testArray.RemoveAll();
testArray.FreeExtra();
}
void CTestMemDlg::OnOK()
{
Test();
CString strInfo;
strInfo.Format("Object construction: %d destruction: %d \r\n",g_cCount,g_dCount);
AfxMessageBox("finish\r\n"+strInfo);
}
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It's a long time since I did any MFC programming, but I suspect that the problem is the definition of CArrayTest. Try making this
typedef CArray<CMyTest,CMyTest> CArrayTest;
(no reference). This will cause every element to be copied into the array, but should work.
If you have an important point to make, don't try to be subtle or clever. Use a pile driver. Hit the point once. Then come back and hit it again. Then hit it a third time - a tremendous whack.
--Winston Churchill
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I think you will find that RemoveAll will remove all the elements from the array but will not actually dispose them (i.e. call their destructors). Should be easy enough to test.
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lostangels wrote:
CArrayTest testArray;
int count = 1000000;<br />
for(int i =0;i < count; i++ )
{
CMyTest testObj;
testObj.m_str = "test string";
testArray.Add(testObj);
}
What will happen if you change this code to
CArrayTest testArray;
int count = 1000000;<br />
testArray.SetSize(count, 100);
for(int i = 0; i < count; i++ )
{
CMyTest testObj;
testObj.m_str = "test string";
testArray.SetAt(i, testObj);
}
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I am not convinced there is a leak ... Please explain this statement
After running the code , it's about 85M memory cannot be release on my computer
How exactly do you know it isn't released?
For example looking at the memory use in Task manager means nothing if that is all you are using. So has this statement got some actual tool basis?
If all you are doing is running task manager run the Test for me twice please one after another.
void CTestMemDlg::OnOK()
{
Test();
test();
CString strInfo;
strInfo.Format("Object construction: %d destruction: %d \r\n",g_cCount,g_dCount);
AfxMessageBox("finish\r\n"+strInfo);
}
If the memory use doesn't double to 170M you aren't leaking memory at all you just misunderstand what windows task manager is reporting.
In vino veritas
modified 6-Jun-16 9:34am.
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How to track for char as input while doing addition for integers. If accidentally given char as input how to prevent it from performing addition calculation.
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You can either
1.) Scan each character of the entry before doing anything with it, this is the generic form of a parser.
2.) Try converting it and if you get an error prompt, reloop and ask for entry again.
3.) Look for an error and if found exit program with error notification.
Which depends on what the source of the number is and what your goals with your program are. For example if the source of the number is a file not much use prompting and asking for re-entry ... files can't do anything about it 
So the question comes down as, in the program you are writing what do you think it should do? What is the most elegant and most useful?
In vino veritas
modified 5-Jun-16 3:13am.
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Can anyone explain me what is the difference in determination value?
double a = 0.0;
double a = .0;
double a = 0.;
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No difference, they all represent the value 0.00, they are just different ways of writing it in source code. You could easily have found this out by writing a small program and stepping through it with your debugger.
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Does exist any document or standard how correct use it forms?
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Sorry, what do you mean by 'correct'? All the examples are correct, in that they declare the value as zero.
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Hi,
I have a Base Class Header File as follows,
class MyClass,typedef void (MyClass::*PFN_DO_SOMETHING)(void* pData);
class MyClass{
PFN_DO_SOMETHING m_pfnDoSomething;
void Act(void* pData);
}
void MyClass::Act(void* pData){
m_pfnDoSomething(pData);
}
Needless to say, 'pfnDoSomething' has been initialised elsewere. I boiled the question down to the essentials, the correct CPP syntax for calling a member function from a pointer to it.
I get a Compiler error stating that 'pfnDoSomething' does not resolve to a function call.
What is the correct syntax for calling this function.
regards 
Bram van Kampen
modified 2-Jun-16 4:00am.
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The solution:
class MyClass{
typedef void (*MyClass::PFN_DO_SOMETHING)(void* pData);
PFN_DO_SOMETHING m_pfnDoSomething;
void Act(void* pData);
};
void MyClass::Act(void* pData){
m_pfnDoSomething(pData);
}
Your errors:
- The asterisk in the
typedef is at the wrong place. - Place the
typedef inside the class to avoid the forward declaration which would not work here with the correct typedef. - The function member name is
m_pfnDoSomething (not pfnDoSomething).
Note also that there is no need to use the class prefix with the typedef. You may also use:
typedef void (*PFN_DO_SOMETHING)(void* pData);
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I've always had difficulty with this, but if memory serves, function pointers in classes are required to be declared static.
[edit]
Memory does not serve.
[/edit]
modified 2-Jun-16 3:16am.
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As per Jochen's answer but I would also add a guard against your forgetting to set the pointer checking it's not NULL. The typecast and advance definition is also unnecessary unless you actually need the type for something, the pointer will be checked for match when you attempt to set it with or without the typecast.
void MyClass::Act(void* pData){
if (m_pfnDoSomething) m_pfnDoSomething(pData);
}
Here is a minimalist function ptr .. no need for forward delaration, typedef or even a name of field. All you need is the * dereference before the function ptr name it knows what you are doing from that and really all it needs is what the function looks like so when you try to set it, that it checks for match.
class MyClass{
void(*MyClass::m_pfnDoSomething)(void*);
void MyClass::Act(void* pData){
if (m_pfnDoSomething) m_pfnDoSomething(pData);
}
};
Finally especially since your in a class I would suggest you don't pass in the void* data pointer but look at other options to typecast or marshal the data in a way that is a little safer.
In vino veritas
modified 4-Jun-16 11:36am.
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How to generate XML file dynamically using C on Linux platform?
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The quick and dirty way it is just matter of printf (and the gcc compiler).
e.g.
#include <stdio.h>
int main(int argc, char * argv[])
{
if (argc != 2) return -1;
printf("<html>\n<head></head>\n<body>\n<p>hello %s, welcome!</p></body></html>", argv[1]);
return 0;
}
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Which part(s) are you having trouble with: creating a file, writing data to that file, forming XML, etc?
"One man's wage rise is another man's price increase." - Harold Wilson
"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons
"You can easily judge the character of a man by how he treats those who can do nothing for him." - James D. Miles
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Hi,
Well, you have to write the Content!
I have no idea of your compiler environment, but, for starters you need to create or select a folder and a File, where the resulting code will be stored. These files would have a 'htm' or 'html' extension. Most environments I know create the Headers and Footers for a blank Page. You have to write the content of the Page in between. You can inspect your work by opening it in Internet Explorer.
Bram van Kampen
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How to determine file offset of each section using RVA in pe file ?
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Quote from Visual Studio, Microsoft Portable Executable and Common Object File Format Specification RVA Relative virtual address. In an image file, the address of an item after it is loaded into memory, with the base address of the image file subtracted from it. The RVA of an item almost always differs from its position within the file on disk (file pointer).
In an object file, an RVA is less meaningful because memory locations are not assigned. In this case, an RVA would be an address within a section (described later in this table), to which a relocation is later applied during linking. For simplicity, a compiler should just set the first RVA in each section to zero.
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I recommend that you read the many books written by Matt Pietreck on the subject. Even books about Win98 or XP will do. They are Classics, but, explain the lot, in your case in particular, how executable files are mapped to memory. I think that this forms part of the foundation every software engineer should have at his finger tips. Matt wrote several books about spelunking in the bowels of the various windows versions. However User Beware! If you are just interested in how your windows version on your computer does things, read, spelunk, and learn! If you start writing software on the basis of what you learn there, BEWARE! It will work, without doubt on Your computer(where you did the Spelunking!) There is absolutely no guarantee that it will work on any other computer, nor, that it will work after the next windows update! Microsoft provides a large API (Application Program Interface), which Microsoft guarantees to support over the various upgrades. Doing things outside this interface, will sooner or later lead to disaster.
Regards,
Bram van Kampen
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