Quote:
Originally Posted by Gene Poole
CString is a class, not a plain old data (POD) type so it behaves differently. The MFC way to deal with this is serialization. All MFC classes derived from CObject support serialization. This is a means of taking all the typically hierarchical data stored in a class structure and converting it to a linear format more appropriate for storing in a stream. You can lookup MSDN help on serialization for more information.
Another approach is to convert the CString to POD types then store those in your file. Since CString is just a bunch of functions for string manipulation and a string buffer, a CString's complete state can be defined by the contents of it's buffer. The buffer is nothing more than a NULL terminated array of characters (either char or wchar_t depending on UNICODE settings--both POD types). You can go about this one of two ways: store an integral value representing the lenght of the string, then the characters themselves (this is sort-of how CString's internal Serialize() function works), or store all the characters and include the NULL terminator. There are advantages and disadvantages to both, so chose whichever is appropriate.
A simple implementation based on your code might look like this (added code in green):
Code:
void CFileOperationsDlg::OnBnClickedButton1()
{
this->UpdateData (TRUE);
CFile f;
CFileException Fexcep;
test buffWrite;
test buffRead;
size_t sz;
TCHAR *buf;
buffWrite .age ="27";
buffWrite .name = "My Name";
f.Open ("E:\\MyFile.bcr", CFile ::modeCreate | CFile ::modeWrite ,&Fexcep);
sz=buffWrite.GetLength();
f.Write(&sz,sizeof(size_t));
f.Write(buffWrite.GetBuffer(),sz*sizeof(TCHAR));
//f.Write (&buffWrite,sizeof(buffWrite ));
buffWrite.ReleaseBuffer();
f.Close ();
if(f.Open("E:\\MyFile.bcr", CFile ::modeRead ,&Fexcep) == FALSE)
return;
try
{
f.Read(&sz,sizeof(size_t);
buf=new TCHAR[sz+1];
f.Read(buf,sz*sizeof(TCHAR));
buf[sz]=0;
buffRead.SetString(buf);
delete[] buf;
//f.Read (&buffRead ,sizeof(buffRead ));
}
catch(CException *e)
{
e->AssertValid ();
}
f.Close ();
}
many thanks for your response.i have done this work,But with the error I faced.please help me.
1>------ Build started: Project: teststring, Configuration: Debug Win32 ------
1>Compiling...
1>teststringDlg.cpp
1>c:\documents and settings\zahra d\desktop\project\teststring\teststring\teststring dlg.cpp(214) : error C2228: left of '.GetLength' must have class/struct/union
1> type is 'TCHAR *'
1>c:\documents and settings\zahra d\desktop\project\teststring\teststring\teststring dlg.cpp(216) : error C2039: 'GetBuffer' : is not a member of 'test'
1> c:\documents and settings\zahra d\desktop\project\teststring\teststring\teststring dlg.cpp(13) : see declaration of 'test'
1>c:\documents and settings\zahra d\desktop\project\teststring\teststring\teststring dlg.cpp(218) : error C2039: 'ReleaseBuffer' : is not a member of 'test'
1> c:\documents and settings\zahra d\desktop\project\teststring\teststring\teststring dlg.cpp(13) : see declaration of 'test'
1>c:\documents and settings\zahra d\desktop\project\teststring\teststring\teststring dlg.cpp(227) : warning C4267: 'argument' : conversion from 'size_t' to 'UINT', possible loss of data
1>c:\documents and settings\zahra d\desktop\project\teststring\teststring\teststring dlg.cpp(229) : error C2039: 'SetString' : is not a member of 'test'
1> c:\documents and settings\zahra d\desktop\project\teststring\teststring\teststring dlg.cpp(13) : see declaration of 'test'
1>Build log was saved at "file://c:\Documents and Settings\zahra d\Desktop\Project\teststring\teststring\Debug\Buil dLog.htm"
1>teststring - 4 error(s), 1 warning(s)
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========