reinterpretcast help . from struct to stream and vice-versa

[tonnot]

I have a stream to store and retrieve values from - to an structure

My_structure {
 int A;
 double B;
};

put (My_structure &value) {
     const char * buffer ;
     buffer = reinterpret_cast<const char*> (&value);
     the_stream.write(buffer,sizeof value);
}

get (My_structure & value) {
    char * buffer ;
    buffer = reinterpret_cast<char*> (&value);
    the_stream.get(buffer, sizeof value);
    value = *reinterpret_cast<My_structure*> (buffer);

}

This compile but I get strange values.... (the tellg and tellp are well pointed to zero before starts the get's)
I dont know how to write this last line (value = ) to get the right values...

Any help would be appreciated.

[LB]

Line 14 makes the buffer point to your structure, so when line 15 goes to copy data there, it'll be in your structure. You don't even need line 16.

[tonnot]

So the "reinterpret" is done when the_stream.get(buffer, sizeof value); is executed ?
It is like 'magic' ????

After the_stream.get(buffer, sizeof value) is exectude,
buffer keeps being a char * , isn't ?

So I dont see the link betwen 'buffer' and 'value'. I dont know how is it possible that 'value 'can get the value 'reinterpreting the bytes'...
How does C++ it ?

[LB]

You're reinterpret_castint one kind of pointer to another (which can be done just fine with a c-style cast), you're not actually reinterpret_casting the class object to a character pointer (which would not work!). Remember, pointers just point to a single memory address, they aren't actually the data itself. Think of pointers as type-safe unsigned longs.