use protobuf

checkout protobuf

svn checkout http://protobuf.googlecode.com/svn/trunk protobuf

compile, install

[dennis@localhost protobuf]$ cd protobuf
[dennis@localhost protobuf]$ sh autogen.sh 
[dennis@localhost protobuf]$ ./configure
[dennis@localhost protobuf]$ make check 
[dennis@localhost protobuf]$ make install

[dennis@localhost protobuf]$ protoc --version
libprotoc 2.5.1

write sample code

[dennis@localhost protobuf]$ mkdir ../google-code-sample
[dennis@localhost protobuf]$ cd ../google-code-sample
[dennis@localhost google-code-sample]$ vim addressbook.proto
[dennis@localhost google-code-sample]$ vim pb_write.cc
[dennis@localhost google-code-sample]$ vim pb_read.cc
[dennis@localhost google-code-sample]$ vim Makefile

cat addressbook.proto

package tutorial;

message Person {
  required string name = 1;
  required int32 id = 2;
  optional string email = 3;

  enum PhoneType {
    MOBILE = 0;
    HOME = 1;
    WORK = 2;
  }

  message PhoneNumber {
    required string number = 1;
    optional PhoneType type = 2 [default = HOME];
  }

  repeated PhoneNumber phone = 4;
}

message AddressBook {
  repeated Person person = 1;
}

cat pb_write.cc

#include <iostream>
#include <fstream>
#include <string>
#include "addressbook.pb.h"
using namespace std;

// This function fills in a Person message based on user input.
void PromptForAddress(tutorial::Person* person) {
  cout << "Enter person ID number: ";
  int id;
  cin >> id;
  person->set_id(id);
  cin.ignore(256, '\n');

  cout << "Enter name: ";
  getline(cin, *person->mutable_name());

  cout << "Enter email address (blank for none): ";
  string email;
  getline(cin, email);
  if (!email.empty()) {
    person->set_email(email);
  }

  while (true) {
    cout << "Enter a phone number (or leave blank to finish): ";
    string number;
    getline(cin, number);
    if (number.empty()) {
      break;
    }

    tutorial::Person::PhoneNumber* phone_number = person->add_phone();
    phone_number->set_number(number);

    cout << "Is this a mobile, home, or work phone? ";
    string type;
    getline(cin, type);
    if (type == "mobile") {
      phone_number->set_type(tutorial::Person::MOBILE);
    } else if (type == "home") {
      phone_number->set_type(tutorial::Person::HOME);
    } else if (type == "work") {
      phone_number->set_type(tutorial::Person::WORK);
    } else {
      cout << "Unknown phone type.  Using default." << endl;
    }
  }
}

// Main function:  Reads the entire address book from a file,
//   adds one person based on user input, then writes it back out to the same
//   file.
int main(int argc, char* argv[]) {
  // Verify that the version of the library that we linked against is
  // compatible with the version of the headers we compiled against.
  GOOGLE_PROTOBUF_VERIFY_VERSION;

  if (argc != 2) {
    cerr << "Usage:  " << argv[0] << " ADDRESS_BOOK_FILE" << endl;
    return -1;
  }

  tutorial::AddressBook address_book;

  {
    // Read the existing address book.
    fstream input(argv[1], ios::in | ios::binary);
    if (!input) {
      cout << argv[1] << ": File not found.  Creating a new file." << endl;
    } else if (!address_book.ParseFromIstream(&input)) {
      cerr << "Failed to parse address book." << endl;
      return -1;
    }
  }

  // Add an address.
  PromptForAddress(address_book.add_person());

  {
    // Write the new address book back to disk.
    fstream output(argv[1], ios::out | ios::trunc | ios::binary);
    if (!address_book.SerializeToOstream(&output)) {
      cerr << "Failed to write address book." << endl;
      return -1;
    }
  }

  // Optional:  Delete all global objects allocated by libprotobuf.
  google::protobuf::ShutdownProtobufLibrary();

  return 0;
}

cat pb_read.cc

#include <iostream>
#include <fstream>
#include <string>
#include "addressbook.pb.h"
using namespace std;

// Iterates though all people in the AddressBook and prints info about them.
void ListPeople(const tutorial::AddressBook& address_book) {
  for (int i = 0; i < address_book.person_size(); i++) {
    const tutorial::Person& person = address_book.person(i);

    cout << "Person ID: " << person.id() << endl;
    cout << "  Name: " << person.name() << endl;
    if (person.has_email()) {
      cout << "  E-mail address: " << person.email() << endl;
    }

    for (int j = 0; j < person.phone_size(); j++) {
      const tutorial::Person::PhoneNumber& phone_number = person.phone(j);

      switch (phone_number.type()) {
        case tutorial::Person::MOBILE:
          cout << "  Mobile phone #: ";
          break;
        case tutorial::Person::HOME:
          cout << "  Home phone #: ";
          break;
        case tutorial::Person::WORK:
          cout << "  Work phone #: ";
          break;
      }
      cout << phone_number.number() << endl;
    }
  }
}

// Main function:  Reads the entire address book from a file and prints all
//   the information inside.
int main(int argc, char* argv[]) {
  // Verify that the version of the library that we linked against is
  // compatible with the version of the headers we compiled against.
  GOOGLE_PROTOBUF_VERIFY_VERSION;

  if (argc != 2) {
    cerr << "Usage:  " << argv[0] << " ADDRESS_BOOK_FILE" << endl;
    return -1;
  }

  tutorial::AddressBook address_book;

  {
    // Read the existing address book.
    fstream input(argv[1], ios::in | ios::binary);
    if (!address_book.ParseFromIstream(&input)) {
      cerr << "Failed to parse address book." << endl;
      return -1;
    }
  }

  ListPeople(address_book);

  // Optional:  Delete all global objects allocated by libprotobuf.
  google::protobuf::ShutdownProtobufLibrary();

  return 0;
}

cat Makefile

CC     = g++
FLAGS  = -Wall
PRO_F  = addressbook
PRO_SRC= $(PRO_F).pb.cc
LIBS   = -lprotobuf
TARGET = pb_write pb_read

all:$(TARGET) 

pb_write: proto_file 
    $(CC) $(FLAGS) $(LIBS) -o $@ pb_write.cc $(PRO_SRC)

pb_read: proto_file 
    $(CC) $(FLAGS) $(LIBS) -o $@ pb_read.cc $(PRO_SRC)

proto_file: $(PRO_F).proto
    protoc -I=./ --cpp_out=./ $(PRO_F).proto

.PHONEY:clean 
clean:
    rm -f $(TARGET) $(OBJS) $(PRO_F).pb.h $(PRO_F).pb.cc

Files:

[dennis@localhost google-code-sample]$ ls
addressbook.proto  Makefile  pb_read.cc  pb_write.cc

Compile and run:

[dennis@localhost google-code-sample]$ make
protoc -I=./ --cpp_out=./ addressbook.proto
g++ -Wall -lprotobuf -o pb_write pb_write.cc addressbook.pb.cc
g++ -Wall -lprotobuf -o pb_read pb_read.cc addressbook.pb.cc
[dennis@localhost google-code-sample]$ ls
addressbook.pb.cc  addressbook.pb.h  addressbook.proto  Makefile  pb_read  pb_read.cc  pb_write  pb_write.cc
[dennis@localhost google-code-sample]$ ./pb_write dennis
dennis: File not found.  Creating a new file.
Enter person ID number: 13
Enter name: dennis
Enter email address (blank for none): dennis.cpp@gmail.com
Enter a phone number (or leave blank to finish): 14159265358
Is this a mobile, home, or work phone? mobile
Enter a phone number (or leave blank to finish): 
[dennis@localhost google-code-sample]$ ./pb_write dennis
Enter person ID number: 19
Enter name: tina
Enter email address (blank for none): tina.mm@gmail.com
Enter a phone number (or leave blank to finish): 21714169628
Is this a mobile, home, or work phone? home 
Enter a phone number (or leave blank to finish): 
[dennis@localhost google-code-sample]$ ./pb_read dennis
Person ID: 13
  Name: dennis
  E-mail address: dennis.cpp@gmail.com
  Mobile phone #: 14159265358
Person ID: 19
  Name: tina
  E-mail address: tina.mm@gmail.com
  Home phone #: 21714169628
[dennis@localhost google-code-sample]$ ls
addressbook.pb.cc  addressbook.pb.h  addressbook.proto  dennis  Makefile  pb_read  pb_read.cc  pb_write  pb_write.cc

Problem:

solution of error while loading shared libraries,
look here
for details.

Reference: