stringstream and binary data
What is needed (some method overrides?) in order to read/write binary data to/from std::basic_stringstream? I am trying the following code, but it does not work as I supposed:
std::basic_stringstream<uint64_t> s;
uint64_t a = 9;
s << a;
uint64_t b;
s >> b;
std::cout << b << std::endl;
but I get "0" printed (built with GCC).
Answer
If you want to read/write binary data you can't use << or >> you need to use the std::stringstream::read and std::stringstream::write functions.
Also you need to use the <char> specialization because only char can safely alias other types.
So you could do it this way:
std::stringstream ss;
std::uint64_t n1 = 1234567890;
ss.write((char const*) &n1, sizeof(n1)); // sizeof(n1) gives the number of char needed
std::uint64_t n2;
ss.read((char*) &n2, sizeof(n2));
std::cout << n2 << '\n';
Output:
1234567890