Writing to the file!

Why does this tell me i'm missing ")"'s?

p.s. Will it work? I'm not sure how to use ofstream great?

Code:

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void fincal2Frame::OnClose(wxCloseEvent &event)
{
    theBar->RemoveIcon();
    fout.open("list.bin");
    for (int i = 0; i < m_TheList->getSize();i++){
        BillData billdat = m_TheList->getDat(i);
        fout.write((char*)&billdat.Cost, sizeof wxString);
        fout.write((char*)&billdat.DueDate, sizeof wxDateTime);
        fout.write((char*)&billdat.Name, sizeof wxString);
    }
    fout.close();
    Destroy();
}

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>Why does this tell me i'm missing ")"'s?
>sizeof wxString
I think you need sizeof(wxString), only because wxString is a class, or you could also write sizeof billdat.Cost.

>p.s. Will it work?
Probably not. Typically writing classes to a file as binary will not work, this only works for simple types. It may write something, but you won't be able to read it later. Also note that if you do write to a file as binary, you should open the file in binary mode.

It's likely using write() won't work, so you'll probably have to write out the actual data instead, separated by either newlines, or some other delimiter like a space:

Code:

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        fout << billdat.Cost << "\n";
        fout << billdat.DueDate << "\n";
        fout << billdat.Name << "\n";

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Classes should serialize themselves. Just do
fout << billdat << "\n";
Overload operators for your class and let it handle the serialization of itself.
This is due to the fact that many times you can't access private members of classes and you don't know what classes may store, what type of data, so if you just store it all, you may corrupt the data they get back.
The class knows itself best, so let it handle read/write.

Ok so my write function works!

Code:

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void fincal2Frame::OnClose(wxCloseEvent &event)
{
    theBar->RemoveIcon();
    fout.open("list.txt");
    for (int i = 0; i < m_TheList->getSize();i++){
        //BillData billdat = m_TheList->getDat(i);
        /*
        fout.write((char*)&billdat.Cost, sizeof wxString);
        fout.write((char*)&billdat.DueDate, sizeof wxDateTime);
        fout.write((char*)&billdat.Name, sizeof wxString);*/
        fout << m_TheList->getCost(i) << "\n";
        fout << m_TheList->getDate(i)<< "\n";
        fout << m_TheList->getName(i) << "\n";
    }
    fout.close();
    Destroy();
}

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and outputs to a file like

Code:

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12
20
The Name

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but i'm having trouble getting it back into the program when it starts. This is what i have so far, but it doesn't work right.

Code:

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    fin.open("list.txt"); //Load the list of bills.
    if (fin && fin.peek()){ // if the file was found.
        while (!fin.eof() ){
        wxString TempName, TempCost;
        int TempDate;
        char buffer[256],buffer2[256];
      // BillData temp("","",wxDateTime::Now());
        fin >> buffer;
        TempCost = _T(buffer);
        fin >> TempDate;
        fin >> buffer2;
        TempName = _T(buffer);
        m_TheList->InsertBill(TempName,TempCost,TempDate);
        }

    }
    fin.close();

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Code:

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fin >> buffer2;

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That only reads one word. Plus char arrays are vulnerable to overflow, so I'd avoid them alltogether. Use std::string, and getline() to get the text data. The numerical stuff, you can use >> my_integer, etc. (Why are you keeping cost in a string?)

Quote:

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Originally Posted by Cactus_Hugger

Code:

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fin >> buffer2;

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That only reads one word. Plus char arrays are vulnerable to overflow, so I'd avoid them alltogether. Use std::string, and getline() to get the text data. The numerical stuff, you can use >> my_integer, etc. (Why are you keeping cost in a string?)

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so somthing like this? I'm confused on how getline works?

Code:

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    fin.open("list.txt"); //Load the list of bills.
    if (fin && fin.peek()){ // if the file was found.
        while (!fin.eof() ){
        std::string TempName, TempCost;
        int TempDate;
        //char buffer[256],buffer2[256];
      // BillData temp("","",wxDateTime::Now());
        fin.getline(TempCost,256,'\n');
        fin >> TempDate;
        fin.getline(TempName,256,'\n');
        m_TheList->InsertBill(TempName,TempCost,TempDate);
        }

    }
    fin.close();

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Sorry - I didn't even know there was a member getline function. There's another : std::getline(istream& is, string& s, char delimiter = '\n'), so:

Code:

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std::string TempName;
std::getline(fin, TempName);
// Convert TempName to a wxString (wxString has a constructor for this)

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ok so i have..

Code:

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    fin.open("list.txt"); //Load the list of bills.
    if (fin && fin.peek()){ // if the file was found.
        while (!fin.eof() ){
        std::string TempName, TempCost;
        int TempDate;
        //char buffer[256],buffer2[256];
      // BillData temp("","",wxDateTime::Now());
        std::getline(fin,TempCost);
        fin >> TempDate;
        std::getline(fin, TempName);
        m_TheList->InsertBill(TempName,TempCost,TempDate);
        }

    }
    fin.close();

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but this is causeing a crash now?

For one thing you shouldn't control the input loop with !eof(). Read the FAQ.

And if TempDate is supposed to be on a separate line you might also have the "input stream leaving newline in the buffer" issue.

Ok it almost works;

write:

Code:

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void fincal2Frame::OnClose(wxCloseEvent &event)
{
    theBar->RemoveIcon();
    fout.open("list.txt");
    fout << m_TheList->getSize() << "\n"; // write the number of units of data to the top of the file
    for (int i = 0; i < m_TheList->getSize();i++){
        fout << m_TheList->getCost(i) << "\n";
        fout << m_TheList->getDate(i)<< "\n";
        fout << m_TheList->getName(i) << "\n";
    }
    fout.close();
    Destroy();
}

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and then the read:

Code:

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    fin.open("list.txt"); //Load the list of bills.
    if (fin && fin.peek()){ // if the file was found.
        int templength;
        fin >> templength;
        fin.ignore(1);
        for(int i=0; i<templength;i++ ){
        std::string TempName, TempCost;
        int TempDate;
        //char buffer[256],buffer2[256];
      // BillData temp("","",wxDateTime::Now());
        std::getline(fin,TempCost);
        fin.ignore(1);
        fin >> TempDate;
        fin.ignore(1);
        std::getline(fin, TempName);
        fin.ignore(1);
        m_TheList->InsertBill(TempName,TempCost,TempDate);
        }

    }
    fin.close();

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although it seems that the date is getting garbled when it's getting read if it's 2 digits long, the second digit is all the makes it in (i.e. 13 becomes 3)

You call fin.ignore(1), which skips the first digit?

Call ignore only after calls to operator>>, not after calls to getline. The call to getline ignores the trailing newline automatically.

Quote:

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Originally Posted by Daved

Call ignore only after calls to operator>>, not after calls to getline. The call to getline ignores the trailing newline automatically.

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ahhh