How to read/write string type member of a struct using binary file in/out in c++?

Question

I have 2 c++ code: one is for write data into a binary file, another is for read that file.

write.cpp code is as below:

#include 

        

Answer 1

The only way that comes to mind is to write the following data separately:

1. Length of the string.
2. The array of characters of the string.
3. The age.

and read them separately.

Create functions to write/read an instance of Data such that they are aware of each other's implementation strategy.

std::ostream& write(std::ostream& out, Data const& data)
{
   size_t len = data.name.size();
   out.write(reinterpret_cast(&len), sizeof(len));
   out.write(data.name.c_str(), len);
   out.write(reinterpret_cast(&data.age));
   return out;
}

std::istream& read(std::istream& in, Data& data)
{
   size_t len;
   in.read(reinterpret_cast(&len), sizeof(len));

   char* name = new char[len+1];
   in.read(name, len);
   name[len] = '\0';
   data.name = name;
   delete [] name;

   in.read(reinterpret_cast(&data.age));
   return in;
}

and use them similarly to your first approach.

Instead of using

people.write(reinterpret_cast(&person),sizeof(person));

use

write(people, person);

Instead of using

people.read(reinterpret_cast(&person),sizeof(person));

use

read(people, person);