Thanks for all this usefull/informative information.
them.
data that follows.
processing.
certain string.
Thanks for the help.
"Joseph M. Newcomer" <newcomer@flounder.com> wrote in message
See below...
On Tue, 22 Apr 2008 13:24:32 GMT, "Kahlua" <kahlua@right.here> wrote:
I have a ListBox with a list of files in the c:\data\ folder with the
extension .dat
Now that I have the file coppied into buffer how do I search through the
buffer
for a specific sequence of bytes?
Thanks,
Ed
void CMyApp::OnSelchangeList()
{
CString mess;
CString JobFile;
char cSelect[50];
****
TCHAR cSelect[MAX_PATH];
at the VERY least. Better still,
CString cSelect;
****
int Length;
int nSelect;
CByteArray buffer;
CFile in;
nSelect=SendDlgItemMessage(IDC_LIST, LB_GETCURSEL, 0, 0L);
****
Why such a crude and antiquated mechanism? Create a control variable for
your list and do
nSelect = c_List.GetCurSel();
note how much easier it is!
****
DlgDirSelect((LPSTR) cSelect, IDC_LIST);
****
Note that DlgDirSelect makes the GetCurSel superfluous, but actually the
simplest thing to
do is to write
c_List.GetText(nSelect, cSelect);
which is a whole lot easier
****
Length=strlen(cSelect);
if (cSelect[Length-1]==0x2e)
cSelect[Length-1]=0;
****
I can't figure out what this is doing because I have no idea what the
purpose of it is.
For example, what in the world is 0x2e? Perhaps you meant to write
if(cSelect[Length-1] == _T(','))
?
If you are testing for a character, it is generally considered good
programming practice
to use the character, and not its hex equivalent.
Also, using the obsolete 'char' data type is not good programming
practice; you should get
the length by writing
Length = _tcslen(cSelect);
But note that this is much more readily written if you have a CString:
if(cSelect.Right(1) == _T("."))
cSelect = cSelect.Left(cSelect.GetLength() - 1);
which is a lot easier to write and understand. Note that you don't need
to get the length
as a separate variable.
****
JobFile = _T("c:\\data\\");
****
You are correctly using _T() here, but in a Unicode build the next line
would fail
****
JobFile += cSelect;
JobFile += ".dat";
****
So why did you use _T() in one literal but not in another?
****
mess = "Would you like to load ";
mess += cSelect;
mess += " as top ?";
****
This would be a lot easier to write as
CString mess;
mess.Format(_T("Would you like to load \"%s\" as top ?"), cSelect);
Note that you do not need to declare the variable at the top; you do not
need to declare
it until it is actually needed. Better still, put that string in the
STRINGTABLE and load
it, so you can localize
****
int a = MessageBox (mess, "Query", MB_ICONINFORMATION|MB_YESNO);
****
int a = AfxMessageBox(mess, MB_ICONQUESTION | MB_YESNO);
It is NOT an information prompt, it is a question prompt. Use
AfxMessageBox, which
follows recommended best practice for the caption (uses the program name).
Use white
space around binary operators to make them legible
****
if (a==IDNO) return;
****
It would be safer to say
if(a != IDYES)
return;
This tests for the actual meaningful value; note the whitespace around the
operator; note
that it uses two lines, which makes it easier to debug.
****
if(!in.Open(JobFile, CFile::modeRead)){
DWORD err = ::GetLastError();
CString msg;
msg.Format(_T("Error opening file: %d"), err);
AfxMessageBox(msg);
return;
}
buffer.SetSize(in.GetLength());
if((INT_PTR)in.Read(buffer.GetData(), buffer.GetSize()) !=
buffer.GetSize()){
DWORD err = ::GetLastError();
CString msg;
msg.Format(_T("Error reading file: %d"), err);
AfxMessageBox(msg);
return;
}
****
Are you searching for text or a binary pattern not expressible as text?
If this is text,
and is known to be 8-bit characters, always, one solution is
CStringA buffer;
LPSTR p = buffer.GetBuffer(in.GetLength());
if((INT_PTR)in.Read(p, in.GetLength()) != in.GetLength())
... as above
buffer.ReleaseBuffer(in.GetLength());
int n = buffer.Find("abc");
if(n < 0)
...not found
else
...found
If you need to find all instances of an 8-bit character string, you would
have a loop, and
the second parameter of Find would give the starting offset for the next
search.
However, if your file is in UTF-8 encoding, you would have to use the
UTF-8 representation
of the string (the most efficient means) or convert the file to a Unicode
representation
(not efficient for large files, especially if the string ends up not being
found). If
your file is potentially Unicode, life gets a good deal more complex, but
I don't want to
get into that here right now.
****
in.Close();
}
Joseph M. Newcomer [MVP]
email: newcomer@flounder.com
Web: http://www.flounder.com
MVP Tips: http://www.flounder.com/mvp_tips.htm