|
How to declare a CALLBACK function by myself?
And how to make it called?
Can you please help me on this.
KIRAN PINJARLA
|
|
|
|
|
A callback is a function that you define but don't call yourself (thought nothing prevents you to do it). A callback is needed whenever you application has to perform some custom actions on occurrence of particular events. For instance, consider the Windows API EnumWindows (see here ^]), for each found window the OS calls the callback you defined (and as you may notice, you have to conform your callback declaration to EnumWindows requested one).
To summarize, usually:
(1) You have to declare you callback as requested by the callback caller.
(2) You may define your callback as you prefer.
(3) You don't call yourself the callback function.
of course the depicted scenario applies to most of the cases, on the other hand, if you are designing, for instance, a framework, then you have to apply the opposite point of view (i.e. establish the callback declaration, let the user application to define it, call the latter whenver appropriate).
Hope that helps.
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.
|
|
|
|
|
|
Hello....I have this function(printinstance()) who generate me randomly boxes(whith another function) with width,height and depth, and I want to save the results in XML, but it only save me just the last box generated...can you figure out what it is the problem in my code please...I have to do this very quick and I am a beginer in XML.
where f-is the first box generated and l-is the last box generated
void printinstance(item *f, item *l, itype W, itype H, itype D)
{ int p,Wcont,Hcont,Dcont;
int const max=1000;
item *i,*j;
itype x1, y1, z1,x2, y2, z2;
stype vol, totvol;
int notip,po;
Wcont=(int)(W);
Hcont=(int)(H);
Dcont=(int)(D);
for (i=f;i<=l;i++)
{
notip=1;
x1 = i->dx; y1 = i->dy; z1 = i->dz;
for (j=i+1;j<=l;j++)
{
if ((i->dx==j->dx)&&(i->dy==j->dy)&&(i->dz==j->dz)) notip++;
}
p=1;
for (j=f;j<i;j++)
if="" ((j-="">dx==i->dx)&&(j->dy==i->dy)&&(j->dz==i->dz))
{
p=0;
break;
}
if (p)
{
x1=i->dx;
y1=i->dy;
z1=i->dz;
XmlTextWriter^ writer = gcnew XmlTextWriter("d:\\contload.xml",Encoding::UTF8);
writer->Formatting = Formatting::Indented;
writer->Indentation=4;
writer->WriteStartDocument();
writer->WriteStartElement("ContainerSolution");
writer->WriteStartElement("ContainerDimensions");
writer->WriteAttributeString("ContainerWidth",W.ToString());
writer->WriteAttributeString("ContainerHeight",H.ToString());
writer->WriteAttributeString("ContainerDepth",D.ToString());
writer->WriteStartElement("Boxes");
writer->WriteAttributeString("BoxWidth",x1.ToString());
writer->WriteAttributeString("BoxHeight",y1.ToString());
writer->WriteAttributeString("BoxDepth",z1.ToString());
writer->WriteEndElement();
writer->WriteEndElement();
writer->WriteEndElement();
writer->WriteEndDocument();
writer->Close();}}}
and I call my function in the main program like this printinstance(f, l, W, H, D);
lavi
|
|
|
|
|
I tried to look through your code but because of HTML reformatting there's some stuff missing.
This is a short function - can't you step through with the debugger?
If it's only writing the last box then single stepping through one iteration should show you why
it's not writing.
Mark
"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder
|
|
|
|
|
When post a code use of pre tags and also its better you asking your questionn on the (Managed) C++/CLI [^]
|
|
|
|
|
lavy2883 wrote: XmlTextWriter^ writer = gcnew XmlTextWriter("d:\\contload.xml",Encoding::UTF8);
Take a closer look at the constuctor ->
http://msdn2.microsoft.com/en-us/library/5366y21d.aspx[^]
MSDN wrote:
Parameters
filename
The filename to write to. If the file exists, it truncates it and overwrites it with the new content.
|
|
|
|
|
Hello All,
I have a problem regarding file. I m trying to open a file using CStdioFile Object like this
test_ptr.Open(File_name,CFile::modeReadWrite,NULL);
i have checked using _access function that this file is present at the desired location or not
int a = _access(File_name,0);
_access is retruning 0 that means file is present but open function is not opening the file (it is also returning zero).
(i have also checked manually file is present at location)
what can be the problem for not opening the file
can anybody help me in this
thanks in advance
|
|
|
|
|
How have you defined test_ptr? If you pass 0 e as the second parameter to _access function, it will check the existence of the file. Use _access function with 6 as the second parameter to check if you have read/write permissions on the file. The following code snippet works perfectly, for me.
CStdioFile test_ptr;
CString File_name = _T("C:\\MyFile.txt"),strTemp;
int iRetCode;
iRetCode = _access(File_name,6);
strTemp.Format(_T("_access function returned %d"),iRetCode);
AfxMessageBox(strTemp);
iRetCode = test_ptr.Open(File_name,CFile::modeReadWrite,NULL);
strTemp.Format(_T("CStdioFile.Open() function returned %d"),iRetCode);
AfxMessageBox(strTemp);
Anything I will say you will bring it down to whatever you want.
|
|
|
|
|
i have passed 6 as second parameter,it returns zero but still not opening file.
|
|
|
|
|
neha.agarwal27 wrote: but still not opening file.
What exactly does that mean? Is CStdioFile.Open() returning zero? Why are you passing a NULL to the Open()command then? Use file exception. Try the following code snippet and find out what the problem is...
CStdioFile test_ptr;
CString File_name = _T("C:\\MyFile.txt"), strTemp;
int iRetCode;
CFileException e;
iRetCode = _access(File_name, 6);
strTemp.Format(_T("_access function returned %d"), iRetCode);
AfxMessageBox(strTemp);
iRetCode = test_ptr.Open(File_name, CFile::modeReadWrite, &e);
if ( !iRetCode )
{
e.GetErrorMessage(strTemp.GetBuffer(MAX_PATH), MAX_PATH, NULL);
AfxMessageBox(strTemp);
strTemp.ReleaseBuffer(-1);
}
else
{
strTemp.Format(_T("CStdioFile.Open() function returned %d"), iRetCode);
AfxMessageBox(strTemp);
}
Anything I will say you will bring it down to whatever you want.
|
|
|
|
|
How to order the Queue in C++
tamer hassan
|
|
|
|
|
What queue class are you using ? The STL includes sort methods.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
"I am working on a project that will convert a FORTRAN code to corresponding C++ code.I am not aware of FORTRAN syntax" ( spotted in the C++/CLI forum )
|
|
|
|
|
What do you mean? Can you explain more clearly?
Steve
|
|
|
|
|
the SHBrowseOfFolder() dialog just give option to directory, i want to give a file list box alongside of directory tree box in the dialog to show the files of selected folder .
How to do?
Or are there any component to use direct? If make it myself, i have to make a tree view, it is a nightmare because i use pure C and API.
|
|
|
|
|
When you add this listbox to the dialog, will users be allowed to select files from the listbox?
If so, then there's another common dialog for that - See GetOpenFileName[^]
If you need to modify the SHBrowseForFolder dialog, then the "Remarks" section of
SHBrowseForFolder Function[^] explains how to get a HWND for the dialog which you can
use to manipulate and/or add controls. You'll probably need to subclass the window to get
notifications when the selected folder changes so you can populate your file list.
zhongwenjia wrote: i have to make a tree view, it is a nightmare because i use pure C and API.
What other way is less of a nightmare? You can wrap the APIs in all the C++ classes you want
but you still end up having to do the same operations on a tree control
Mark
"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder
|
|
|
|
|
how to differenciate the empty value (. . . .) and 0.0.0.0 in ip address control.
I used
CWnd* pwndCtrl = GetFocus();
int ctrl_ID = pwndCtrl->GetDlgCtrlID();
if (!((CIPAddressCtrl*)pwndCtrl)->IsBlank())
but it treat the . . . . and 0.0.0.0 values as same.
|
|
|
|
|
You are not initializing the control. Use ClearAddress() function in OnInitDialog(). It will display 0.0.0.0 from start.
|
|
|
|
|
after calling the Clearaddress() also its not displaying the 0.0.0.0
CWnd* pwndCtrl = GetFocus();
((CIPAddressCtrl*)pwndCtrl)->ClearAddress();
could you please suggest
|
|
|
|
|
Hello all
I have an information on a hard disk with unknown format which the windows cannot recognize it. and it is very urgent now for me to make a backup. so I am asking for a very low level tool to make a backup for my drives.
|
|
|
|
|
try this
http://www.freedownloadscenter.com/Best/hex-disk-editor.html
|
|
|
|
|
Hi,
I have a C#.net application in which i have read the datas from excel sheet and displayed in a datagrid in my Aspx form.
The code is here
private void Button2_Click(object sender, System.EventArgs e)
{
try
{
string strConnection = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\Salary.xls;Extended Properties=""Excel 8.0;HDR=YES;""";
OleDbConnection conn = new OleDbConnection(strConnection);
//conn.Open();
OleDbCommand command = new OleDbCommand("SELECT * FROM [Sheet1$]", conn);
// command.Connection = conn;
// command.CommandType = CommandType.Text;
// command.CommandText = "SELECT * FROM [Sheet1]";
OleDbDataAdapter da = new OleDbDataAdapter(command);
DataSet ds = new DataSet();
//DataTable dt = new DataTable();
conn.Open();
da.Fill(ds, "EmpSal");
DataGrid1.DataSource=ds;
DataGrid1.DataBind();
//da.Fill(dt);
conn.Close();
lblError.Text="The Excel sheet has been read";
//return dt;
}
catch (Exception ex)
{
Response.Write( ex.Message);
//return null;
}
}
the thing is that i have to upload the datas into the mysql database table. can anybody pls help me with the C#.net code. i need to use only mysql database.(coz we r using mysql db in our project)
Regards
Vijay.
|
|
|
|
|
Posting a C# .NET question in the Visual C++ forum will end in tears. - Chris Maunder
Anything I will say you will bring it down to whatever you want.
|
|
|
|
|
Sorry chris, i didn't intentionally do it. i was in a puzzly mood at the time of posting this question and it ended up mismatched. once again I apologize for my mistake.
Vijay.
|
|
|
|
|
Dear friends,
I am new to vc++. I am writing an application that executes a dos command which generates some files. I can user CreateProcess methid to call the dos command. But I want to exit the function only after the completion of dos command. Is it possible? I heared that I can use WaitForSingleObject. Could any body teach me how to write this?
thanks
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
