Question

I am trying to use this example:

std::size_t s2 = boost::asio::buffer_size(buffer);
const void* p2 = boost::asio::buffer_cast<const void*>(buffer);

And I am getting a vaild size s2 and some seemingly valid address p2.

Now, how could I create a cout or printf loop or phrase a debug-statement, to see the content of p2?

I bet this is quite basic, but currently I can’t see what I am missing.

Tried this:

std::cout << "TEST: " << boost::asio::buffer_cast<const void*>(buffer) << std::endl;

but it only prints out the address, not the content

and this:

for(int i =0; i!=s2; i++){
    std::cout << "TEST: " << p2[i];
}
std::cout << std::endl;

but I am ending up with compile errors, like C0253 – unknown size.

So, how can I print out the content of p2?

Answer 1

You can print the bytes pointed to by buffer as:

std::size_t s2 = boost::asio::buffer_size(buffer);
const void* p2 = boost::asio::buffer_cast<const void*>(buffer);

unsigned char const* bytes = static_cast<unsigned char const*>(p2);
for(std::size_t i = 0 ; i < s2 ; ++i)
     std::cout << static_cast<unsigned int>(bytes[i]);

Of course, you have to interpret the output.

You can print the hexadecimal values instead which is easier to interpret:

std::cout << std::hex << static_cast<unsigned int>(bytes[i]);
          // ^^^^^^^^ note this

I think you have to #include<iomanip> for this.