Problem with file IO

Hi,

I am fairly new to C++. My problem is that my project won't compile ever since I've added very simple code for file output.

Code:

---

#include "iostream.h"
#include "fstream.h"
...
...
...
ofstream outfile;
char filename[] = "c:/example.txt";
outfile.open(filename, ios::out);
if (!outfile)
        {
        cerr << "Can't open output file " << filename << endl;
        return;
        }
outfile << table << endl;
outfile.close();
return;

---

Above is just a chunk of the cpp file. "table" is a CString object containing 280x320 temperature values. I have been able to display a portion of it using an AfxMessageBox function, but I want to save all the values to a file. I am using Visual Studio .NET 2003, and I read somewhere that .NET doesn't have all the necessary library files. That makes NO sense to me but either way, I got myself the header files "iostream.h" and "fstream.h" and added them to my project. I still get the same compiling errors as before, saying (summarized):

Quote:

---

error C2065: 'cerr' : undeclared identifier
error C2065: 'endl' : undeclared identifier
error C2065: 'ofstream' : undeclared identifier
error C2065: 'out' : undeclared identifier
error C2065: 'outfile' : undeclared identifier
error C2146: syntax error : missing ';' before identifier 'outfile'
error C2228: left of '.close' must have class/struct/union type
type is ''unknown-type''
error C2228: left of '.open' must have class/struct/union type
type is ''unknown-type''
error C2593: 'operator <<' is ambiguous
error C2653: 'ios' : is not a class or namespace name
error C3861: 'endl': identifier not found, even with argument-dependent lookup
error C3861: 'outfile': identifier not found, even with argument-dependent lookup

---

Does anyone know what I need to do to get it working? to get it to save "table" to a file"? Have I done something wrong? Thanks.

Chunky

You should use include <iostream> and using namespace std not "iostream.h"

>> I read somewhere that .NET doesn't have all the necessary library files.
The VC++ 2003 compiler and later versions don't come with iostream.h and fstream.h because those are non-standard headers. They are old versions that were used before there were standards. You should be using <iostream> and <fstream> without the .h, and as Micko said you must indicate that you are using the std namespace. This is a common issue so a look at the FAQ or a search might provide more information.

Also, whatever tutorial, book, or learning source you got the code from is probably pretty outdated. The C++ library has been standardized since 1998. Consider finding a more up-to-date reference.

I tried it but there's no change. Thanks anyways Micko.

Can it be the location of the header files? I saved them in the same folder as the other header files from the same project.

Are there different versions of fstream and iostream? Can it be that I have a wrong ones? How can I tell that fstream and iostream do what I need?

Thanks

wait, did you move the iostream headers from the default directory into your project folder? don't do that.

Thanks Daved, I'll keep looking.

Quote:

---

wait, did you move the iostream headers from the default directory into your project folder? don't do that.

---

Hi Indigo0086, that is where I originally saved them. I copied iostream.h and fstream.h from a coworkers VC++ and saved them in my project folder. I'm not sure which is the default folder, but I will try "Microsoft Visual Studio .NET 2003\Vc7\include". Thanks.

Don't use iostream.h or fstream.h. Delete them from your hard drive. In your code, use #include <iostream> and #include <fstream> and add using namespace std;. If you still get errors, post those.

BTW, don't delete the files called iostream and fstream in your compiler's include directory, I'm talking about getting rid of the iostream.h and fstream.h (with the '.h') that you copied from your co-worker's machine.

Ok, iostream.h and fstream.h are unfindable on my hard drive. They're gone. The first 3 lines of my code are:

Code:

---

#include <iostream>
#include <fstream>
using namespace std

---

Nothing else has been changed. I'm still getting the same errors as before, except this time I'm abbreviating a little less.

Code:

---

error C2065: 'cerr' : undeclared identifier
error C2065: 'endl' : undeclared identifier
error C2065: 'ofstream' : undeclared identifier
error C2065: 'out' : undeclared identifier
error C2065: 'outfile' : undeclared identifier
error C2146: syntax error : missing ';' before identifier 'outfile'
error C2228: left of '.close' must have class/struct/union type
        type is ''unknown-type''
error C2228: left of '.open' must have class/struct/union type
        type is ''unknown-type''
error C2561: 'CFSWinView::ShowImage' : function must return a value
        c:\Documents and Settings\HP_Administrator\My Documents\Working Copies\Copy of FSWin\FSWinView.h(84) : see declaration of 'CFSWinView::ShowImage'
error C2593: 'operator <<' is ambiguous
        c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\atlmfc\include\afxstr.h(154): could be 'CDumpContext &operator <<<char,StrTraitMFC_DLL<_CharType>>(CDumpContext &,const ATL::CStringT<BaseType,StringTraits> &)'
        with
        [
            _CharType=char,
            BaseType=char,
            StringTraits=StrTraitMFC_DLL<char>
        ]
        c:\Program Files\Microsoft Visual Studio .NET 2003\Vc7\atlmfc\include\afxstr.h(108): or      'CArchive &operator <<<char,StrTraitMFC_DLL<_CharType>>(CArchive &,const ATL::CStringT<BaseType,StringTraits> &)'
        with
        [
            _CharType=char,
            BaseType=char,
            StringTraits=StrTraitMFC_DLL<char>
        ]
        while trying to match the argument list '('unknown-type', CString)'
error C2653: 'ios' : is not a class or namespace name
error C3861: 'endl': identifier not found, even with argument-dependent lookup
error C3861: 'outfile': identifier not found, even with argument-dependent lookup
error C3861: 'outfile': identifier not found, even with argument-dependent lookup
error C3861: 'outfile': identifier not found, even with argument-dependent lookup
error C3861: 'outfile': identifier not found, even with argument-dependent lookup

---

There's obviously something else going on here. Any ideas? :)

using namespace std;

same

Maybe there was an error when you installed your ide/compiler. Did you use an exe installer or just copied the files to your hd.

If it can't find iostream, it should give an error that it cannot find the include file. Since it didn't give that error, that means it found iostream just fine. Then, it doesn't recognize cerr, which is declared in iostream. That usually means that it isn't getting the namespace correct, but you said you have "using namespace std;" under the #include's so that shouldn't be a problem. It is very odd that the compiler would be able to find iostream and fstream but not find the stuff inside if you are using the namespace correctly.

Is the cerr error the very first one on the list?

post the rest of the file, maybe there's more to it that's causing the error.

Thanks again for taking the time to look my work.

Quote:

---

Is the cerr error the very first one on the list?

---

Yes.


I created a project using the following code (copied from an online tutorial) and it works fine, does exactly what it should.

Code:

---

// basic file operations
#include <iostream>
#include <fstream>
using namespace std;

int main () {
  ofstream myfile;
  myfile.open ("example.txt");
  myfile << "Writing this to a file.\n";
  myfile.close();
  return 0;
}

---

So I'm guessing my installation is fine and there must be something different about my code that's giving me problems.
I copied a lot more of my code below. I copied the #includes and declarations exactly as they appear, a small section on debugging (don't understand, thought it could be relevant), and the portion of code that I'm working on. Using the "Visual C++.NET Bible", I added a different method of file i/o (METHOD1)for which my project compiles. But when I debug it, I get an assertion error in a file called afxole.inl at line 166. (Everything within the 2 "test//test//test" comments is code added by me, otherwise, it was part of the original program)

Code:

---

// FSWinView.cpp : implementation of the CFSWinView class
//
///////////////////////
//// TEST // TEST /////
#include <iostream>///
#include <fstream>///
using namespace std;///
//// TEST // TEST /////
///////////////////////
#include "stdafx.h"
#include "FSWin.h"

#include "camera.h"
#include "FSWinDoc.h"
#include "FSWinView.h"
#include "FPFDlg.h"
#include "fpfimg.h"
#include "AlarmSettings.h"
#include ".\fswinview.h"
...
...
...
#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif
...
...
...
#ifdef _DEBUG
void CFSWinView::AssertValid() const
{
        CFormView::AssertValid();
}

void CFSWinView::Dump(CDumpContext& dc) const
{
        CFormView::Dump(dc);
}

CFSWinDoc* CFSWinView::GetDocument() // non-debug version is inline
{
        ASSERT(m_pDocument->IsKindOf(RUNTIME_CLASS(CFSWinDoc)));
        return (CFSWinDoc*)m_pDocument;
}
#endif //_DEBUG
...
...
...
int CFSWinView::ShowImage(int nImageType)
{
        VARIANT va = m_Camera.GetImage(nImageType);

        // Check validity of returned image
        VARTYPE vt = (nImageType < 2 ? VT_I2 : (nImageType < 4 ? VT_R4 : VT_UI1));
    if (va.vt == VT_I2) // Error
        return (int)va.iVal;

        if (va.vt != (VT_ARRAY | vt))
                return -1;

        COleSafeArray sa;
        sa.Attach(va);
//////////////////////////////////////////////////////////////////////
////// TEST /// TEST /// TEST /// TEST /// TEST /// TEST /// TEST ////////////////////////
        // Display dimensions of the array stored in "sa".
        long w, h;
        CString s, msg, table;
        s.Format(_T("Dimensions: %d\n"), sa.GetDim());
        msg += s;
        sa.GetUBound(1, &w);
        sa.GetUBound(2, &h);
        w++;
        h++;
        s.Format(_T("Width of array: %ld\n"), w);
        msg += s;
        s.Format(_T("Height of array: %ld\n"), h);
        msg += s;
        AfxMessageBox(msg);
       
        // Display contents of "sa" (array of Kelvin temperature values) in the CString object "table".
        float HUGEP *a_image;
        sa.AccessData((void HUGEP **)&a_image);
        for (int x=0 ; x<10 ; x++) // x<10 should be x<w
        {
                for (int y=0 ; y<10 ; y++) // y<10 should be y<h
                {
                        s.Format("%4.2f  ", a_image[w*x+y]);
                        table += s;
                }
                s.Format(_T("\n"));
                table += s;
        }
////////////////////// NEW STUFF /////////////////////// (I got this from the "Visual C++ .NET Bible)
        // Display contents of "table" in a text file. (Method 1)
        HANDLE hFile = ::CreateFile("example.txt",
                                        GENERIC_READ,
                                        FILE_SHARE_READ,
                                        0,
                                        OPEN_EXISTING,
                                        FILE_ATTRIBUTE_NORMAL,
                                        NULL);
        HANDLE pFile; //pFile was not defined in the Bible's example, so I added this.
        if (hFile)
        {
                CFile file(hFile);
                if (file.Open("example.txt", CFile::modeWrite))
                {
                        try
                        {
                                file.SeekToEnd(); // Go to end of file so as to not overwrite existing data.
                                file.Write(table, strlen(table));
                                file.Close();
                        }
                        catch(CFileException* pe)
                        {
                                pe->ReportError();
                                if (pFile)
                                {
                                        delete pFile;
                                }
                        }
                }
        }

///////////////////// END OF NEW STUFF //////////////////////
/*        // Display contents of "table" in a text file. (Method 2)
        ofstream outfile;
        char filename[] = "c:/example.txt";
        outfile.open(filename, ios::out);
        if (!outfile) // Test file open.
        {
                cerr << "Can't open output file " << filename << endl;
                return;
        }
        outfile << table << endl;
        outfile.close();
*/
///// TEST /// TEST /// TEST /// TEST /// TEST /// TEST /// TEST ////////////////////////
//////////////////////////////////////////////////////////////////////
        DisplayImage(nImageType, sa);
        VariantClear(&va);
        return 0;
}

---

Oh ya, and based on what you said Daved,

Quote:

---

That usually means that it isn't getting the namespace correct, but you said you have "using namespace std;" under the #include's so that shouldn't be a problem.

---

, I wasn't sure if the using namespace std needed to be inserted in a particular location, so I tried many different ones (ie. just before the object that's giving me problems; at the very beginning; under the #includes), but got the same problem.

Sorry, one last thing, there is nothing between #include ".\fswinview.h" and #ifdef _DEBUG. I added the ... by mistake.

The stdafx.h header shows the problem. The compiler ignores everything that comes before that include directive. Remove it and turn off precompiled headers in the project options.

It now looks like this:

Code:

---

// FSWinView.cpp : implementation of the CFSWinView class
//
#include "stdafx.h"
#include "FSWin.h"
///////////////////////
//// TEST // TEST /////
#include <iostream> ///
#include <fstream>  ///
using namespace std;///
//// TEST // TEST /////
///////////////////////
#include "camera.h"
#include "FSWinDoc.h"
...

---

That fixed the compiling, awesome! I didn't need to remove the #include "stdafx.h" or turn off precompiled headers. Thanks CornedBee. But I still get the assertion error during debugging. The problem is caused by something in this section:

Code:

---

// Display contents of "sa" (array of Kelvin temperature values) in the CString object "table".
        float HUGEP *a_image;
        sa.AccessData((void HUGEP **)&a_image);
        for (int x=0 ; x<10 ; x++) // x<10 should be x<w
        {
                for (int y=0 ; y<10 ; y++) // y<10 should be y<h
                {
                        s.Format("%4.2f  ", a_image[w*x+y]);
                        table += s;
                }
                s.Format(_T("\n"));
                table += s;
        }

---

Any ideas?

Get rid of the HUGEP thing. It's a relict from 16-bit Windows. But that's not the actual problem, so what type is sa? Are you sure the loop limits are correct? (The comments hint at a possible problem.) What's the value of w - it is used in the array access, but not in the loop itself, which is a bit weird. Which line exactly causes the assertion? The debugger should be able to tell you that, and also exactly what invalid value (typically) caused it.

"sa" is defined earlier as a COleSafeArray object. It can be seen in the code I posted on page 2 of this thread, and below. Note: "va" is an array of floating point values.

Code:

---

COleSafeArray sa;
        sa.Attach(va);

---

I'm pretty sure my loop limits are correct. While I was testing with AfxMessageBox, I set the loops to only display a portion of the array. I added those comments so that I would remember to eventually change them back. Below shows how w and h are defined. When executed, w= 320 and h=240.

Code:

---

long w, h;
        ... ... ...
        sa.GetUBound(1, &w);
        sa.GetUBound(2, &h);
        w++;
        h++;

---

The exact error message I get is:

Quote:

---

Microsoft Visual C++ Debug Library

Debug Assertion Failed!

Program: ...tor\My Documents\Working Copies\Copy of FSWin\Debug\FSWin.exe
File: f:\vs70builds\3077\vc\MFCATL\ship\atlmfc\include\a fxole.inl
Line: 166

For information on how your program can cause an assertion failure, see the Visual C++ documentation on asserts.

(Press Retry to debug the application)

---

If the debugger tells me more, I don't know where to find it.

I'm a huge dope. I fixed it. I was using the COleSafeArray member "AccessData" without subsequently using "UnaccessData". Once I added that to my code, I was no longer getting the failed assertion.

Thanks for all your help!
Kind regards,
Chunky