ChecksumExample

    // ------------------------------- //
    // -------- Start of File -------- //
    // ------------------------------- //
    // ----------------------------------------------------------- //
    // C++ Source Code File Name: testprog.cpp
    // Compiler Used: MSVC, BCC32, GCC, HPUX aCC, SOLARIS CC
    // Produced By: DataReel Software Development Team
    // File Creation Date: 02/04/1997
    // Date Last Modified: 06/17/2016
    // Copyright (c) 2001-2016 DataReel Software Development
    // ----------------------------------------------------------- //
    // ------------- Program Description and Details ------------- //
    // ----------------------------------------------------------- //
    /*
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public
    License along with this library; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
    USA

    gxDatabase persistent checksum example.
    */
    // ----------------------------------------------------------- //
    #include "gxdlcode.h"

    #if defined (__USE_ANSI_CPP__) // Use the ANSI Standard C++ library
    #include <iostream>
    #include <iomanip>
    using namespace std; // Use unqualified names for Standard C++ library
    #else // Use the old iostream library by default
    #include <iostream.h>
    #include <iomanip.h>
    #endif // __USE_ANSI_CPP__

    #include <string.h>
    #include "gxdbase.h"
    #include "gxfloat.h"
    #include "gxdstats.h"

    const int name_length = 16;

    class DatabaseObject
    {
    public:
      DatabaseObject() { name[0] = 0; oid = (gxINT32)0, cid = (gxFLOAT64)0; }
      DatabaseObject(const char *s, long i, double d);

    public:
      void DisplayObject();

    public: // Platform independent data members
      char name[name_length]; // Fixed string type
      gxINT32 oid;            // Integer type
      gxFLOAT64 cid;          // Floating point type
    };

    DatabaseObject::DatabaseObject(const char *s, long i, double d)
    {
      for(int j = 0; j < name_length; j++) name[j] = 0; // Clear the name string
      strcpy(name, s);
      oid = i;
      cid = d;
    }

    void DatabaseObject::DisplayObject()
    {
      cout << "Database object name: " << name << "\n";
      cout << "Database object OID:  " << oid << "\n";
      cout.setf(ios::showpoint | ios::fixed);
      cout.precision(3);
      cout << "Database object CID:  " << cid << "\n";
    }

    void PausePrg()
    {
      cout << "\n";
      cout << "Press enter to continue..." << "\n";
      cin.get();
    }

    int main(int argv, char **argc)
    {
      char rev_letter = 'D'; // Set the revision letter
      if(argv == 2) { // Set a specified revision letter
        rev_letter = *argc[1];
        if(rev_letter == '0') rev_letter = 0;
        // Valid persistent record lock rev letters are:
        // Rev 'A' or 'a'
        // Rev 'B' or 'b'
        // Rev 'C' or 'c'
        // Rev 'D' or 'd'
      }

      gxDatabase *f = new gxDatabase;
      if(!f) {
        cout << "Error allocating memory for database file pointer..." << "\n";
        return 1;
      }
      const char *fname = "simple.gxd";
      int exists;

      cout << "\n";
      cout << "Simple checksum example." << "\n";

      if(!gxDatabase::Exists(fname)) {
        cout << "Creating new file..." << "\n";
        f->Create(fname, (FAU_t)0, rev_letter);
        if(CheckError(f) != 0) {
          delete f;
          return 1;
        }
        exists = 0;
      }
      else {
        cout << "Opening existing file..." << "\n";
        f->Open(fname);
        if(CheckError(f) != 0) {
          delete f;
          return 1;
        }
        exists = 1;
      }

      PausePrg();
      DatabaseStats(f);
      PausePrg();

      FAU addr;
      int rv;
      __ULWORD__ object_crc, calc_crc;

      if(!exists) {
        cout << "Adding object to database file..." << "\n";
        // Allocate a block to store the object
        addr = f->Alloc(sizeof(DatabaseObject));

        // Construct the datbase object
        DatabaseObject ob("Mouse", (long)addr, 1035.101);

        f->Write(&ob, sizeof(DatabaseObject));

        f->WriteObjectChecksum(addr);
        f->ReadObjectChecksum(addr, &object_crc, &calc_crc);
        cout.setf(ios::uppercase);
        cout << "Object CRC =     0x" << setfill('0') << setw(8) << hex
    	 << object_crc << "\n";
        cout << "Calculated CRC = 0x" << setfill('0') << setw(8) << hex
    	 << calc_crc << dec << "\n";
        BlockStats(f, addr);
      }
      else {
        f->Open(fname);
        cout << "Reading the first object from the database file..." << "\n";
        addr = f->FindFirstBlock();

        // CRC checksum routines
        rv = f->ReadObjectChecksum(addr+f->BlockHeaderSize(),
    			       &object_crc, &calc_crc);
        if(!rv) cout << "Checksum error!" << "\n";
        cout.setf(ios::uppercase);
        cout << "Object CRC =     0x" << setfill('0') << setw(8) << hex
    	 << object_crc << "\n";
        cout << "Calculated CRC = 0x" << setfill('0') << setw(8) << hex
    	 << calc_crc << dec << "\n";
        cout.unsetf(ios::uppercase);
        cout << "\n";

        DatabaseObject buf;
        f->Read(&buf, sizeof(DatabaseObject), addr+f->BlockHeaderSize());
        buf.DisplayObject();
      }

      cout << "Exiting..." << "\n";
      f->Close();
      if(CheckError(f) != 0) {
        delete f;
        return 1;
      }

      delete f;
      return 0;
    }
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