FileToGrid (C++)

Description

The following example uses a button, a string grid, and an Open dialog box on a form. When you click the button, you are prompted for a file name. When you click OK,the specified file is opened, read into a buffer, and closed. Then the buffer is displayed in two columns of the string grid. The first time you use this application, you should do a "Fill Grid" and then a "Write Grid to File". Always use files generated like this to do a "Read File into Grid".

Read File to Grid

Code

void __fastcall TForm1::Button1Click(TObject *Sender)
{
  int iFileHandle;
  int iFileLength;
  int iBytesRead;
  int iLength;
  int count;
  wchar_t *pszBuffer;
  if (OpenDialog1->Execute())
  {
        try
        {
          iFileHandle = FileOpen(OpenDialog1->FileName, fmOpenRead);
      iFileLength = FileSeek(iFileHandle,0,2);
          FileSeek(iFileHandle,0,0);
          iBytesRead = FileRead(iFileHandle, &count, 4);
          StringGrid1->ColCount = count;
          iBytesRead = FileRead(iFileHandle, &count, 4);
          StringGrid1->RowCount = count;
          for (int x = 0; x < StringGrid1->ColCount; x++)
          {
                for (int y = 0; y < StringGrid1->RowCount; y++)
                {
                  // Write out the length of each string, followed by the string itself.
                  FileRead(iFileHandle, &iLength, 4);
                  pszBuffer = new wchar_t[iLength + 1];
 
                  FileRead(iFileHandle, pszBuffer, iLength*sizeof(wchar_t));
                  pszBuffer[iLength] = 0;
                  StringGrid1->Cells[x][y] = pszBuffer;
                  delete [] pszBuffer;
                }
          }
          FileClose(iFileHandle);
          delete [] pszBuffer;
        }
    catch(...)
        {
#if defined(_DELPHI_STRING_UNICODE)
          Application->MessageBox(
                L"Can't perform one of the following file operations: Open, Seek, Read, Close.",
                L"File Error",
                IDOK);
#else
          Application->MessageBox(
                "Can't perform one of the following file operations: Open, Seek, Read, Close.",
                "File Error",
                IDOK);
#endif
        }
  }
}
 
// Write Grid into File
 
#include <dir.h>
 
void __fastcall TForm1::Button2Click(TObject *Sender)
{
  wchar_t szFileName[MAXFILE+4];
  int iFileHandle;
  int iLength;
  int count;
  if (SaveDialog1->Execute())
  {
        if (FileExists(SaveDialog1->FileName))
    {
          _wfnsplit(SaveDialog1->FileName.c_str(), 0, 0, szFileName, 0);
 
 
          wcscat(szFileName, L".BAK");
          //Removing previously created .BAK files, if found
          if (FileExists(szFileName)) {
                  DeleteFileW(szFileName);
          }
          RenameFile(SaveDialog1->FileName, szFileName);
    }
        iFileHandle = FileCreate(SaveDialog1->FileName);
        // Write out the number of rows and columns in the grid.
        count = StringGrid1->ColCount;
        FileWrite(iFileHandle, &count, sizeof(count));
        count = StringGrid1->RowCount;
        FileWrite(iFileHandle, &count, sizeof(count));
        for (int x=0;x<StringGrid1->ColCount;x++)
        {
          for (int y=0;y<StringGrid1->RowCount;y++)
          {
                // Write out the length of each string, followed by the string itself.
                iLength = StringGrid1->Cells[x][y].Length();
                FileWrite(iFileHandle, (wchar_t *)&iLength, sizeof(iLength));
                FileWrite(iFileHandle, StringGrid1->Cells[x][y].w_str(), StringGrid1->Cells[x][y].Length()*sizeof(wchar_t));
          }
        }
        FileClose(iFileHandle);
  }
}

Uses

• System.SysUtils.FileExists ( fr | de | ja )
• System.SysUtils.FileOpen ( fr | de | ja )
• System.SysUtils.FileSeek ( fr | de | ja )
• System.SysUtils.FileRead ( fr | de | ja )
• System.SysUtils.FileWrite ( fr | de | ja )
• System.SysUtils.FileClose ( fr | de | ja )