C / C++ / MFC

29-May-08 20:46

Hi all,

One of my application I used MFC(actually CFile) to find the file size in easy way.

Now I thought to do it using standard C++. Here is my try.

size_t file_size;
ifstream in_file;

    in_file.open("C:\\temo_file.txt", ios_base::in);

if(in_file.is_open())
{
    file_size = in_file.seekg(-1, ios_base::end).tellg();
    cout << file_size;
}

My question is, this code gives misses one byte. Can you guys give me any reason for it.

Thanks

I appreciate your help all the time...
CodingLover Smile | :)

Doc Lobster29-May-08 21:44

Doc Lobster

29-May-08 21:44

I guess with seekg you are looking for the position -1 from the end. Therefore you are missing the byte.

Additionally look here:
http://www.codeproject.com/KB/files/filesize.aspx[^]

http://www.cplusplus.com/reference/iostream/istream/seekg.html[^]

CodingLover29-May-08 22:26

29-May-08 22:26

Thanks for links.

I appreciate your help all the time...
CodingLover Smile | :)

CPallini29-May-08 22:06

29-May-08 22:06

CodingLover wrote:
file_size = in_file.seekg(-1, ios_base::end).tellg();

should be

file_size = in_file.seekg(0, ios_base::end).tellg();

BTW you may also use GetFileSize [^].

Smile | :)

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

CodingLover29-May-08 22:22

29-May-08 22:22

Thanks, so my attempt is not bad. Smile | :)

Is that GetFileName is standard C++. I'm confusing with those.

I appreciate your help all the time...
CodingLover Smile | :)

CPallini29-May-08 22:34

29-May-08 22:34

CodingLover wrote:
Is that GetFileName is standard C++. I'm confusing with those.

Nope. It is provided by Win32 API. If you just need to avoid MFC that's is fine, on the other hand, if you need to be stuck with C++ standard, then use ifstream.
Smile | :)

CodingLover29-May-08 22:39

29-May-08 22:39

Since I start to learn C++, confusing with this. Is that best way to work with standard C++? Sometimes I feel that use of MFC easy than standard C++, and other way too. Appreciate your explanation on it.

I appreciate your help all the time...
CodingLover Smile | :)

CPallini29-May-08 23:03

29-May-08 23:03

Using C++ standard you write code that will execute also on different platforms (for instance Linux). On the other hand, if you need to exploit Windows not-portable functionalities (like the GUI components¹) the you have to use Win32 API or MFC. GUI development with MFC is usually simpler.
Smile | :)

(¹) There are exceptions: for instance QT [^] is a framework that enable you to write portable GUI code.

CodingLover29-May-08 23:07

29-May-08 23:07

Ok, as I said now I have mixture of them. If I want to learn standard C++ from where I should begin.

I appreciate your help all the time...
CodingLover Smile | :)

CPallini29-May-08 23:19

29-May-08 23:19

What about "The C++ Programming Language" [^] book of Stroustrup?
Smile | :)

CodingLover30-May-08 2:33

Changing the no. of rows and cols in MsFlexGrid dynamically

30-May-08 2:33

Thanks a lot. Smile | :)

I appreciate your help all the time...
CodingLover Smile | :)

sunny_vc29-May-08 20:24

sunny_vc

29-May-08 20:24

Hi all,
Is there any option to change the number of rows and cols dynamically in a flexgrid??

Thanks,

Regards,
Sunil Kumar

Re: Changing the no. of rows and cols in MsFlexGrid dynamically

Nelek29-May-08 21:05

Nelek

29-May-08 21:05

I don't know in flexgrid, but in Listctrl I made it by deleting all and redrawing the control with the new number of elements.

Greetings.
--------
M.D.V. Wink | ;)

If something has a solution... Why do we have to worry about?. If it has no solution... For what reason do we have to worry about?
Help me to understand what I'm saying, and I'll explain it better to you
“The First Rule of Program Optimization: Don't do it. The Second Rule of Program Optimization (for experts only!): Don't do it yet.” - Michael A. Jackson
Rating helpfull answers is nice, but saying thanks can be even nicer.

Re: Changing the no. of rows and cols in MsFlexGrid dynamically

MANISH RASTOGI29-May-08 21:17

MANISH RASTOGI

29-May-08 21:17

Changes Rows and Cols property.

Re: Changing the no. of rows and cols in MsFlexGrid dynamically

Chandrasekharan P30-May-08 1:21

Chandrasekharan P

30-May-08 1:21

u can use the functions SetRows and SetCols to set the rows and cols dynamically...

Pageheap working in MFC App but not Win32 console?

ohming29-May-08 18:29

ohming

29-May-08 18:29

I am learning to use pageheap.
I created a MFC App(pageheaptestdlg.exe) with memory corruptiong bug and compiled it in release mode.
I enabled pageheap by gflags /p /enable pageheaptestdlg /full
Then run debugger ntsd -g -x pageheaptestdlg.
It has something like:
===========================================================
VERIFIER STOP 00000008: pid 0xDF8: corrupted suffix pattern

015B1000 : Heap handle
01682FF8 : Heap block
00000005 : Block size
00000000 :
===========================================================

However it is not the same for console app.
I created a Win32 Console Application with memory corruption bug and compiled it in release mode.
I enabled pageheap by gflags /p /enable pageheaptest /full
Then run debugger ntsd -g -x pageheaptest.
There is no message regarding the corrupted suffix pattern. Why?

Source code:

// PageHeapTest.cpp : Defines the entry point for the console application.
//

#include "stdafx.h"

int main(int argc, char* argv[])
{
	int len = 5;
	char *a = new char[len];
	a[len] = 6;
	delete [] a;

	return 0;
}

writing a device context from one application to another

Llasus29-May-08 18:22

Re: writing a device context from one application to another

29-May-08 18:22

Hello and good day. I have an application which writes writes an image in a picture box and does processing in it about every 200ms. Now, I need to show the image being written into another application's picture box. I'm currently looking for ways to do this and currently I'm thinking of using clipboard. I want to know if there are better ways of doing this. Looking for any suggestions/solutions regarding this.
Thank you in advance. Smile | :)

SandipG 29-May-08 19:33

SandipG

29-May-08 19:33

How you planning to synchronize two applications??

Re: writing a device context from one application to another

Llasus29-May-08 19:38

Re: writing a device context from one application to another

29-May-08 19:38

i was just thinking of using mutex if I am going to implement the clipboard solution.

SandipG 29-May-08 19:44

SandipG

29-May-08 19:44

I feel clipboard would be used by many applications so avoid it.
You can use memory mapped files instead. It all depends on your requirements but it just a suggestion.

Re: writing a device context from one application to another

Llasus29-May-08 19:53

Re: writing a device context from one application to another [modified]

29-May-08 19:53

SandipG wrote:
I feel clipboard would be used by many applications so avoid it.

yes, that might cause problems later on.

SandipG wrote:
You can use memory mapped files instead. It all depends on your requirements but it just a suggestion.

thank you for the suggestion. I'll check this one out. though from what I've read, this might be slower than a standard file I/O. The image in the application is refreshed per 200ms. But I'll try to make some dummy application and check if it works. Again, thanks a lot. Smile | :)

SandipG 29-May-08 20:00

SandipG

29-May-08 20:00

one more suggestion.
You can have a common DLL and have one static variable ~~of (HBITMAP/CBitmap/Image/Bitmap)~~ may be you have to use pixel data in the form of byte array or someting similar and use the dll in both the applications.
I hope it makes sense.

modified on Monday, June 23, 2008 2:46 AM

Re: writing a device context from one application to another [modified]

Llasus29-May-08 20:11