C / C++ / MFC

17-Jan-07 23:54

i created xml file need to read, the file read the data ( Sniff | :^)

??? might be !!
not sure ,
when i print that data in the messagebox it gives the square box like.

hFile=CreateFile ( L"c:\\FileProperty.XML"
                         , GENERIC_READ | GENERIC_WRITE
                         , FILE_SHARE_READ
                         , NULL
                         , OPEN_EXISTING
                         , FILE_ATTRIBUTE_NORMAL
                         , NULL
                         );

	if(hFile == INVALID_HANDLE_VALUE)
	{
		MessageBox(0,_T("File is not created"),_T("Create File"),0);		
	}
	else
	{	
	MessageBox(0,_T("File is created"),_T("Create File"),0);	
	}

/*
	
	dwFileSize = GetFileSize (hFile, &dwHighSize) ;
	
	if (dwHighSize)
     {
          CloseHandle (hFile) ;
          //return NULL ;
     }

     
	szBuff=malloc (dwFileSize) ;

     if (!szBuff)
     {
          CloseHandle (hFile) ;
          //return NULL ;
     }
 */
	
	 
	bool bSucced=ReadFile(hFile,&szBuff,5000,&dwRecvLen,NULL);		
	szBuff[dwRecvLen] = '\0';	
	MessageBox(0,LPCWSTR(szBuff),L"Message",0);

how can i print that data in the string form?.

amit

Roger Stoltz18-Jan-07 0:23

18-Jan-07 0:23

Well, there seems to be a some errors in the code you posted.

You seem to have made the memory allocation for szBuff out-commented.
You assume that the file size doesn't exceed 5000 bytes.
I don't exactly get what you mean by "square box like", but I guess that you have enabled unicode for your build configuration and the first bytes in the "string" you want to display evaluates to a token that doesn't match a writeable character.
You even type cast to a LPCWSTR, which in this case doesn't have any effect since the MessageBox parameter is dependant on whether you have enabled unicode support or not.

The bottom line is that you have to be consistant: if you have enabled unicode support then you have to make sure that the file data is converted unless the file is already in unicode format, which I suspect it's not and that's what I think gives the result you've described.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote

amitmistry_petlad 18-Jan-07 0:30

18-Jan-07 0:30

ya exactly , i forget to write that thing D'Oh! | :doh:

its unicode thats why its come like
square box but how can do it in readable form?
because the messagebox show the unicode character so how to make that data to
read meaningful.
ok i made that file unicode then will it give me the data in the proper
readable form?

amit

Roger Stoltz18-Jan-07 0:41

18-Jan-07 0:41

amitmistry_petlad wrote:
ok i made that file unicode then will it give me the data in the proper
readable form?

Technically: yes.
But, perhaps other applications that are supposed to use the file may no longer use it since you've changed the file format.

My suggestion:
Read the file as usual and then convert to unicode with ::MultiByteToWideChar().

"It's supposed to be hard, otherwise anybody could do it!" - selfquote

amitmistry_petlad 18-Jan-07 1:10

18-Jan-07 1:10

But for that how can i convert my DWORD TO string look the following code:
Smile | :)

std::string source(szBuff); //or source=szBuff 	

	WCHAR w_Out[MAX_PATH];
	MultiByteToWideChar(CP_ACP,MB_PRECOMPOSED,source.c_str(),(int)(source.length() + 1),w_Out,MAX_PATH);	


	MessageBox(0,LPCWSTR(w_Out),L"Message",0);

amit

Roger Stoltz18-Jan-07 2:05

18-Jan-07 2:05

amitmistry_petlad wrote:
DWORD

What DWORD?
If you mean values read from the xml-file, you can convert them from textual format into DWORDs by calling ::wcstol().
I'm just guessing that the above is your problem. If it's not, describe it further.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote

amitmistry_petlad 18-Jan-07 16:36

18-Jan-07 16:36

i think you might forget the previous code so Cool | :cool:

,
look i explain with detail code .

WCHAR szBuff[5000]={}; // which i have declare global

//below is my function which used the gelobal variable szBuff read data from file

void _FilePersistandata()
{
	//int MAX_RCV_LEN=5000;
	HANDLE	hFile;
	DWORD    dwFileSize, dwHighSize, dwBytesRead ;
	
	DWORD dwRecvLen = 0;


	hFile=CreateFile ( L"c:\\FileProperty.XML"
                         , GENERIC_READ | GENERIC_WRITE
                         , FILE_SHARE_READ
                         , NULL
                         , OPEN_EXISTING
                         , FILE_ATTRIBUTE_NORMAL
                         , NULL
                         );

	if(hFile == INVALID_HANDLE_VALUE)
	{
		MessageBox(0,_T("File is not created"),_T("Create File"),0);		
	}
	else
	{	
	MessageBox(0,_T("File is created"),_T("Create File"),0);	
	}

	
	 
	bool bSucced=ReadFile(hFile,<big>&szBuff</big>,5000,&dwRecvLen,NULL);		//bold is DWORD 

	szBuff[dwRecvLen] = '\0';	//this is dword
	<code>
	//the following is required conversion for string. 
	std::string source(szBuff);	//FOR MultiByteToWideChar i have did the follwing i havent excat idea about but the code is follwing. 
</code>
	WCHAR w_Out[MAX_PATH];
	MultiByteToWideChar(CP_ACP,MB_PRECOMPOSED,source.c_str(),(int)(source.length() + 1),w_Out,MAX_PATH);	


	MessageBox(0,LPCWSTR(w_Out),L"Message",0);	


}

let me know if something is wrong here ,then i'll change it.

amit

Roger Stoltz18-Jan-07 21:19

18-Jan-07 21:19

Instead of making assumptions about my memory, you should get your datatypes straight.

The things you claim to be DWORD is never DWORD in the code you've posted.
You declare szBuff as an array of WCHAR and WCHAR is a typedef that can be either 8 or 16 bits wide, but never 32 as a DWORD. In your configuration it's 16 bits wide since you've enabled support for unicode.
The only thing about szBuff that is 32 bits wide is its address you provide as argument in the call to ReadFile, but do not mix up an address with a 32 bit integer value.

ReadFile read the contents of a file in raw format, i.e. byte-wise, and puts it at a memory location you provide as argument, szBuff in your case. If the format of the data read doesn't fit your needs, convert it! In this case by calling MultiByteToWideChar providing the buffer with the data read as input and a pointer to a new location where you want the resulting data to be stored.
Bring up the memory debug window and have a look at your <codes>zBuff. After a successful call to ReadFile you will see the contents of your file there.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote

amitmistry_petlad 18-Jan-07 0:41

18-Jan-07 0:41

ok thanks its done

heap or stack?

himuskanhere17-Jan-07 23:30

himuskanhere

17-Jan-07 23:30

hello friends

char ch[10];
Cstring str ="Rahul"

memset(ch,0,10);///set ch to '\0';

memcpy(ch,str,5);

plz tell me where ch will be stored..on heap or on stack..thanks

Born To Code

toxcct17-Jan-07 23:46

toxcct

17-Jan-07 23:46

as you don't allocate it with a new, it will be in the stack...

Don't know where to start ?
Refer the Forums Guidelines and ask a friend

[VisualCalc 3.0][Flags Beginner's Guide]

Roger Stoltz17-Jan-07 23:51

17-Jan-07 23:51

Both of your variables will be located on the stack. Even the 10 bytes referred to by ch will be located on the stack.

To use the heap you have to allocate memory by calling new in C++ or malloc or similar in C and you always get a pointer in return to be able to refer to the allocated memory.

"It's supposed to be hard, otherwise anybody could do it!" - selfquote

James R. Twine18-Jan-07 6:08

James R. Twine

18-Jan-07 6:08

rahul.shendurnikar wrote:
char ch[10];
CString str ="Rahul"

Both of those allocate the specified objects on the stack - that is, the array of char and the CString object will be allocated on the stack.

However, note the memory used by the CString object will be allocated on the heap, because that is how CStrings work. In other words, you are causing two kinds of allocations when really only one is required. Oh, and since heap allocation operations can raise exceptions, you should be assigning to that string object in a try/catch block just to be safe! Smile | :)

Note that you are getting really lucky by using memcpy to copy into the string object's buffer - that is generally not the correct way to get data into or out of a real object.

Peace!

-=- James
Please rate this message - let me know if I helped or not!<HR>If you think it costs a lot to do it right, just wait until you find out how much it costs to do it wrong!
Avoid driving a vehicle taller than you and remember that Professional Driver on Closed Course does not mean your Dumb Ass on a Public Road!
See DeleteFXPFiles

Mark Salsbery18-Jan-07 6:36

Mark Salsbery

18-Jan-07 6:36

James R. Twine wrote:
Note that you are getting really lucky by using memcpy to copy into the string object's buffer - that is generally not the correct way to get data into or out of a real object.

Where is he doing that? Smile | :)

James R. Twine18-Jan-07 8:27

James R. Twine

18-Jan-07 8:27

You are correct - he is copying out of it, but only by the grace of CString::operator LPCTSTR(). My warnings still stand, though.

Peace!