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I'd like to pass a string from an app to another using a user-defined message and SendMessageI'm receving the message but when i typecast wParam, I do not get my string but "IIIIIIIII...III" even if types and memory address match in both application when debugging.
What's wrong ?
~RaGE();
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You can not pass pointers from one process (that is Adress Spece) to another.
You can pass them from thread to thread, but not from app to app.
The memory has a different use in the other address space.
Insted, you have to use e.g. the clipboard, a memory mapped file, or (I am not sure) GlobalAlloc might work.
My opinions may have changed, but not the fact that I am right.
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Typecast as
CString* pString = (CString*)l; // l is the lParam value
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jhwurmbach is basically right:
The adress space is different between processes (i.e. the same virtual address refers to different physical locations, and you might not even have access rights to that location)
A typical solution would be a memory mapped file (relatively easy to create, yet quite flexible).
Another option is a WM_COPYDATA message. You will receive a copy of the data (but this is valid only while the message is processed, so create your own copy on the client side)
for a CString:
Sender:
CString myString = ...
COPYDATASTRUCT cds;
cds.dwData = 0;
cds.cbSize = (myString.GetLength()+1) * sizeof(TCHAR);
cds.lpData = (LPCTSTR) myString;
::SendMessage(hwndReceiver, WM_COPYDATA, (WPARAM) hwndSender, (LPARAM) &cds); Receiver - WM_COPYDATA handler:
HWND sender = (HWND) wParam;
COPYDATASTRUCT & cds = *(COPYDATASTRUCT *)cds.lpData;
CString receivedString = (LPCTSTR) cds.lpData;
Note: this does not handle passing from UNICODE app to ASCII/MBCS app (or vice versa) correctly
"Der Geist des Kriegers ist erwacht / Ich hab die Macht" StS
sighist | Agile Programming | doxygen
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peterchen wrote:
The adress space is different between processes (i.e. the same virtual address refers to different physical locations, and you might not even have access rights to that location)
Ok .. Did not know about that ... that would explain why memory address would match without containing the value. Why is this working, then :
::SendMessage(hwndReceiver, WM_MSG, (WPARAM) hwndSender, (LPARAM) "Yopyop");
and
CString receivedString = (LPCTSTR) lParam;
peterchen wrote:
A typical solution would be a memory mapped file (relatively easy to create, yet quite flexible).
Just checked MSDN (found CMemFile), it seems to be exactly what I need ni this case.
Big thanks to all of you guys !!  (I should tell Chris to add a Thanks everybody between Reply and Mail so that not only the last message gets all the thanks  )
~RaGE();
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If you send that message between 2 instances of the same application, it could work because "Yopyop" will be in a fixed position (as its a string literal) in the EXE file(and memory). But you dont get the same "Yopyop" it just looks like that 
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Thank you for explaining that!![Rose | [Rose]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/rose.gif) ![Beer | [beer]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/beer.gif)
His reply left me cluless why this should work. But your explanation is great!
My opinions may have changed, but not the fact that I am right.
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Rage wrote:
Why is this working, then?
You could be lucky 
Or, if it's the same binary, you're just passing a pointer into the data segment. As EXE's are usually mapped to the same beginning address, it works most of the time.
CMemFile is not the right thing, it's just a file in "normal" memory, but not shared between processes.
Look up CreateFileMapping and MapViewOfFile in the Win32 documentation.
And I said "relatively easy" - it's just a way to share some memory between two applications. Instead of the pointer, both sides would need to agree on a common name for the mapping - it's recommended to include a GUID in the name of the mapping - and you would have to e.g. pass an offset to the actual string. if it's just about a string, use WM_COPYDATA.
"Der Geist des Kriegers ist erwacht / Ich hab die Macht" StS
sighist | Agile Programming | doxygen
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You guys are all making this task way too difficult.
Here's the simple solution:
ATOM A = GlobalAddAtom( _T("The String that I want to send") );
SendMessage( hWnd, msg, wParam, (LPARAM)A);
// -- at the other end
TCHAR buf[255];
GlobalGetAtomName( (ATOM)lParam, buf, 255 );
GlobalDeleteAtom( (ATOM)lParam)
// you've got your string.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br />
Peter Weyzen<br />
Staff Engineer<br />
Santa Cruz Networks
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Can anyone please tell me that how can i define the operator << for datatype like _int64
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Its the same as any other operator<<.
MyObj& operator<<(__int64 i64Value)
__int64 is an MS extension so that can be a problem depending on which compiler you are trying to compile on.
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Assuming you want to emit it to an ostream (hard to tell without you telling what you want to do with it), the follwing will do.
std::ostream& operator<<(std::ostream& os, UINT64 i)
{
char sz[32];
sprintf(sz, "%I64u", i);
os << sz;
return os;
}
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This is how I create my window:
<br />
m_hWnd=CreateWindow("STATIC",lpszName,WS_CHILD|WS_VISIBLE|WS_CLIPSIBLINGS,nX,nY,nWidth,nHeight,hParent,NULL,hInstance,NULL);<br />
It's a static window with a dialog as a parent.
Now I want to add a border to it, specificaly the "sunken" effect.
<br />
CWnd* pWnd=CWnd::FromHandle(m_hWnd);<br />
pWnd->ModifyStyleEx(0,WS_EX_CLIENTEDGE);<br />
The function returns TRUE, but I don't see any border around my static window.
Is this the right way to do it? Did I make an error?
using: [VISUAL STUDIO 6.0 sp5] [WIN98/2]
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Use pWnd->ModifyStyleEx(0,WS_EX_CLIENTEDGE, SWP_DRAWFRAME);
rechi
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That's it tnx
using: [VISUAL STUDIO 6.0 sp5] [WIN98/2]
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I need your help
How to embbed a simple window into dialogbox (modeless) using CreateWindowEx function?.
I really need that one
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My questions are these;
How can I ensure that a program which creates a file is the only one allowed to access that file? And furthermore how can I make windows clean up my temporary files (in case the program crashes or something)? Taking into consideration that the program which created the file has some sort of security lock on the file.
Something clever should be said, but I don't have the time
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1. you can't do it directly in Windows. Windows does not support file locking or access validity of any form. Only access level rights of a file are checked while accessing a file, which comes from the current user's access rights and privileges.
Probable solution:
You need to put some sort of file encryption algo so that only authorize process/program can open it to read/write data from/into the file. but one draw back there in this. anyone can corrupt the file and data will be lost beyound recovery.
2. A
tmp files can be deleted by a countom made software that looks for special file name patters and if found can take appropriate action of deletion.. this SW can be put to start during Windows startup so that by teh time PC is ready to be used all tmp files are deleted.
2. B
also tmp file names can be logged in one common file with complete path. this file can be opened by a SW during Windows startup and all entries in that file can be deleted one by one. tmp file paths will be added to this log file by various processes/programs that require peroidic/auto deletion of log files.
techi !!
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BhaskarBora wrote:
1. you can't do it directly in Windows. Windows does not support file locking or access validity of any form. Only access level rights of a file are checked while accessing a file, which comes from the current user's access rights and privileges.
What rubbish. See the dwShareMode param of CreateFile().
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/base/createfile.asp[^]
2. This is trying to clean up after the fact. Far better to prevent the problem in the first place.
Neville Franks, Author of ED for Windows. Free Trial at www.getsoft.com
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"What rubbish. See the dwShareMode param of CreateFile(). "
CreateFile will work till you have opened the file and after u close it any process can open it and read the contents.
requirement is that no other process should be able to even open or read the file, which was originally created by some other process. this can be done by encrypting the file whose descryption is known to only the creator of the file.
_________________________________________________________________
"Think big, think fast, think ahead. Ideas are no one's monopoly"
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Raggamuffin wrote:
How can I ensure that a program which creates a file is the only one allowed to access that file?
See the dwShareMode param of CreateFile(). Sharemode can be also spec'd in some other functions that wrap CreateFile(). See: http://msdn.microsoft.com/library/default.asp?url=/library/en-us/fileio/base/createfile.asp[^]
Raggamuffin wrote:
And furthermore how can I make windows clean up my temporary files (in case the program crashes or something)?
1) Use C++ and/or Structured Exception Handling (SEH). There are several good articles here on CP about Exception Handling.
2) Use RAII to manage the file handle and simply rely on destructors to cleanup for you. Boost scoped_ptr will do this for you very nicely. See: http://www.boost.org/libs/smart_ptr/scoped_ptr.htm[^]
Neville Franks, Author of ED for Windows. Free Trial at www.getsoft.com
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Hiya I have to structure and wanted to make a pointer to it WITH 10 INSTANCES.
So I have:
struct s_Test
{
char name[30];
}
struct s_Test* Test[10];
void main()
{
memcpy( Test[0]->name,"Paul",30 ); // system error here
return;
}
My problem happens when I go to access an element of the structure. I gives me the system error that the app must close.
Any ideas how to access them properly??
Thanks;
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Try to use a std:vector of std:string. That works.
If you really cant use C++ and MUST continue to use C, then this one works:
#include "stdafx.h"
#include < memory.h >
struct s_Test
{
char name[30];
};
int main(int argc, char* argv[])
{
struct s_Test Test[10];
memcpy( Test[0].name,"Paul",30 );
return 0;
}
My opinions may have changed, but not the fact that I am right.
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Meeeep. System error. Copying 30 characters from a buffer which is only 5 characters ("Paul"+zero) long.
-Dominik
_outp(0x64, 0xAD);
and
__asm mov al, 0xAD __asm out 0x64, al
do the same... but what do they do??
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OOOPS! 
But it did compile.....
That type of errors is the reason why I prefer std::vector and std::string.
My opinions may have changed, but not the fact that I am right.
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