Question

char data_[4096];
...
socket_.async_read_some(boost::asio::buffer(data_, 4096),
    boost::bind(&client::handle_read_header, this,
    boost::asio::placeholders::error,
    boost::asio::placeholders::bytes_transferred));

when function handle_read_header is fired, data_ contains many \0 symbols in text.
with help of which way is it easier to view full (with stripped or escaped \0) string by std::cout? (by default \0 make end of string and don’t show other)

Answer 1

Seth kindly pointed out your requirement to make it “easier to view”. For that:

for (size_t i = 0; i < num_bytes; ++i)
    if (buffer[i] == '\\')
        std::cout << "\\\\";
    else if (isprint(buffer[i]))
        std::cout << buffer[i];
    else
        std::cout << '\\' << std::fill(0) << std::setw(3) << buffer[i];

The above uses 3-digit back-slash escaped octal notation to represent non-printable characters. You can change the representation easily enough.

(For a simple binary write, you can call std::cout.write(buffer, num_bytes) to do a binary block write, rather than std::cout << buffer which relies on the ASCIIZ convention for character arrays/pointers. Then you could pipe the result into less, cat -vt or whatever your OS provides that helps view binary data including NULs.)