C / C++ / MFC

file.write((char*)&objdata,sizeof(Data));

file.write((char*)&(objdata.id),sizeof(objdata.id));
string::size_type len = objdata.name.length();
file.write((char*) &len, sizeof(len)); // this is useful for reading back the string
file.write((char*)(objdata.name.c_str(), len); //note: not storing null terminator

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

class Data
{
public:
	char name[20];
	int id;
public:
	Data(){}
	Data(char *n,int id){strcpy(name,n);this->id=id;}
};

int main() {

	Data objdata;
	//fstream file("c:\\test.txt",ios::out | ios::binary);
	fstream file("c:\\test.txt",ios::in | ios::binary);
	if(file.is_open())
	{
		//file.write((char*)&objdata,sizeof(Data));

		file.read((char*)&objdata,sizeof(Data));
		cout<<objdata.name<<objdata.id;
		cout<<"Success";
		file.close();
	}
	else
	{
		cout<<"Error";
	}

	return 0;
}

lazy_panther wrote:

Any pointers what am I doing wrong?

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

int main() {
  // write some characters in binary mode
  fstream file("C:\\test.txt",  ios::out | ios::binary);
  char out[]="hello";
  file.write(out, sizeof(out));
  file.close();
  
  // read the written characters
  file.open("C:\\test.txt", ios::in | ios::binary);
  char in[sizeof(out)];
  file.read(in, sizeof(in));
  cout << out << ", " << in << endl;
  file.close();
  
  return 0;
}

fstream file("c:\\test.txt",ios::in | ios::binary);
if(file.is_open())
{
   std::string s;
   file >> s;
   std::cout << s << std::endl; 
   file.close();
}
else
{
   cout<<"Error";
}