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Save from and load to Array of Struct

Posted on 2001-08-20
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Last Modified: 2013-12-14
Hello All;

I am relatively new to C++ programming and having a little difficulty...

I have an Array of Struct, consisting of about 15 CStrings and 10 booleans.  The array as 20 elements.

I am trying to figure out the simplest way to save the data in this array to a file, then later reload the array with the data from the file.

In case it's relevant, I'm using Microsoft eVC++ for the Pocket PC.

Thanks,

Paul
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Comment
Question by:prstein
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11 Comments
 
LVL 86

Expert Comment

by:jkr
ID: 6407540
If you want to keep these structs containing MFC CStrings, I'm afraid that you'll have to go for the MFC serialization concept...
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LVL 1

Author Comment

by:prstein
ID: 6407625
Hello jkr;

Thanks for that hint.  I just took a quick look at serialization in the help file, and it *couldn't* be more tedious than what I'm currently doing (which is converting to and from a csv format).

If you (or anyone) can provide a sample, the points are yours.

Regards,

Paul
0
 
LVL 9

Expert Comment

by:ShaunWilde
ID: 6407756
for saving

struct
{
  BOOL b;
  CString s;
} xstr;


xstr x[20];


CFile f;
if( !f.Open( pFileName, CFile::modeCreate | CFile::modeWrite ) ) {
   #ifdef _DEBUG
      afxDump << "Unable to open file" << "\n";
      exit( 1 );
   #endif
}
CArchive ar( &f, CArchive::store);

for (int i=0;i<20;i++)
{
  ar << x[i].b;
  ar << x[i].s
}

f.Close();


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LVL 9

Expert Comment

by:ShaunWilde
ID: 6407775
for loading

CFile f;
if( !f.Open( pFileName, CFile::modeRead ) ) {
  #ifdef _DEBUG
     afxDump << "Unable to open file" << "\n";
     exit( 1 );
  #endif
}
CArchive ar( &f, CArchive::load);

for (int i=0;i<20;i++)
{
 ar >> x[i].b;
 ar >> x[i].s
}

f.Close();
0
 
LVL 4

Expert Comment

by:AssafLavie
ID: 6407960
Or, using std C++ output/input operators:

#include <iostream>
#include <fstream>
#include <sstream>
#include <vector>
#include <string>
using namespace std;


struct c
{
     string a, b;
     bool e, f, g;
};

ostream& operator<< (ostream& o, const c& c1)
{
     o << c1.e << " " << c1.f << " " << c1.g << " ";
     o << c1.a.length() << " " << c1.a;
     return o << c1.b.length() << " " << c1.b;
};

istream& operator>> (istream& in, c& c1)
{
     in >> c1.e >> c1.f >> c1.g;

     size_t size;
     char szBuff[100];

     in >> size;
     in.read(szBuff, size);
     c1.a.assign(szBuff, size);

     in >> size;
     in.read(szBuff, size);
     c1.b.assign(szBuff, size);
     // etc
     return in;
};
void main(short ac,char **av)
{
     vector<c> vc;
     fstream f("target.file");
     copy(vc.begin(), vc.end(), ostream_iterator<c>(f, " "));
     vector<c> target;
     while (!f.eof())
     {
          c c1;
          f >> c1;
          target.push_back(c1);
     };
}
0
 

Expert Comment

by:Samuel082001
ID: 6408252
I believe for this question, you will have to use the <fstream.h> header file, where you open a file for writing and write the data in the array of structure in the file.
ofstream fout(filename);
fout<<data;
.........
fout.close();
when you want to read from the file,
ifstream fin(filename);
fin>>data;
fin.get(ch);
or
fin.getline(ch, 50, '\n');
anything else, just contact me.
0
 
LVL 1

Author Comment

by:prstein
ID: 6408443
Hello ShaunWilde (and everyone);

I tried your suggestion, modified as follows:

void CLibraryEditView::OnButtonSaveLibrary()
{
     CFile f;

     TCHAR* pFileName = _T("\\My Documents\\Library\\TempLib1.lib");

     if( !f.Open( pFileName, CFile::modeCreate | CFile::modeWrite ) )
     {
          #ifdef _DEBUG
               afxDump << "Unable to open file" << "\n";
               exit( 1 );
          #endif
     }

     CArchive ar ( &f, CArchive::store);
     for (int i=0;i<2;i++)
     {
          ar << m_pPV->m_pLib[i].LibIsotopeName;
          ar << m_pPV->m_pLib[i].LibkeV1;
          ar << m_pPV->m_pLib[i].LibYield1;
          ar << m_pPV->m_pLib[i].LibComment1;
          ar << m_pPV->m_pLib[i].LibPri1;
          ar << m_pPV->m_pLib[i].LibSec1;

          ar << m_pPV->m_pLib[i].LibkeV2;
          ar << m_pPV->m_pLib[i].LibYield2;
          ar << m_pPV->m_pLib[i].LibComment2;
          ar << m_pPV->m_pLib[i].LibPri2;
          ar << m_pPV->m_pLib[i].LibSec2;

          ar << m_pPV->m_pLib[i].LibkeV3;
          ar << m_pPV->m_pLib[i].LibYield3;
          ar << m_pPV->m_pLib[i].LibComment3;
          ar << m_pPV->m_pLib[i].LibPri3;
          ar << m_pPV->m_pLib[i].LibSec3;

          ar << m_pPV->m_pLib[i].LibkeV4;
          ar << m_pPV->m_pLib[i].LibYield4;
          ar << m_pPV->m_pLib[i].LibComment4;
          ar << m_pPV->m_pLib[i].LibPri4;
          ar << m_pPV->m_pLib[i].LibSec4;

          ar << m_pPV->m_pLib[i].LibkeV5;
          ar << m_pPV->m_pLib[i].LibYield5;
          ar << m_pPV->m_pLib[i].LibComment5;
          ar << m_pPV->m_pLib[i].LibPri5;
          ar << m_pPV->m_pLib[i].LibSec5;
     }

     f.Close();
}

It compiles and runs fine, but gives the message "an unnamed file was not found".  A file with the appropriate name is created that contains 0 bytes (but does not overwrite or update if the file already exists).

So close, and yet so far...

Paul
0
 

Expert Comment

by:Samuel082001
ID: 6408599
I don't think your program code above wrote anything to the file. Maybe that's why the file you created contains 0 bytes. or, there could be a possibility that the directory of the file is written wrongly. This could also cause such an error. Check your code again.
0
 
LVL 9

Accepted Solution

by:
ShaunWilde earned 300 total points
ID: 6408830
my fault - I forgot the following calls before f.Close()

     ar.Flush();
     ar.Close();

 
0
 
LVL 1

Author Comment

by:prstein
ID: 6409400
ShaunWilde;

Thanks for persisting through this.  Well done!

Regards,

Paul
0
 
LVL 9

Expert Comment

by:ShaunWilde
ID: 6409496
no probs - glad to help
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