Serializing Strings

[echoscot]

I have to serialize some string data to a binary file:

example:

string name = "My Name";

ofstream fout("file.dat", ios:ut|ios::binary)

int size = name.size();

fout.write(reinterpret_cast<char*>(&size), sizeof(int));

fout.write(reinterpret_cast<char*>(&name), sizeof(size));

fout.read(reinterpret_cast<char*>(&size), sizeof(int));

fout.read(reinterpret_cast<char*>(&name), sizeof(size));

cout<<" name is: "<<name;

the above crashes just after printing "name is ", then won't print the string it just crashes. Also have tried variations, like write/read((char*)&name, sizeof(string)),

wondering if there is a specific trick to this?

 

[uolj]

You should write the string's data, not the sring itself, since it is not a POD:

fout.write(reinterpret_cast<char*>(&name.data()), size);

There's some other issues with that code (you shouldn't read from an ofstream). When you do read you should be reading into a vector or a temporary char array, and then transferring into the string, since you cannot directly modify the contents of a string.

vector<char> temp(size);
fin.read(reinterpret_cast<char*>(&temp[0]), size);
name.assign(temp.begin(), temp.end());

My syntax might be a bit off but that's the idea.

 

[echoscot]

Thank you that is very helpful about the vector/array to read into. I actually did set up a separate ifstream object, unlike the pseudocode I posted.