Why is stringstreams rdbuf() and str() giving me different output?

Question

I have this code,

int main()
{
    std::string st;
    std::stringstream ss;
    ss<<"hej hej med dig"<<std::endl;

    std::getline(ss,st,' ');
    std::cout <<"ss.rdbuf()->str() : " << ss.rdbuf()->str();
    std::cout <<"ss.rdbuf() : " << ss.rdbuf();
    return 0;
}

Giving me this output

ss.rdbuf()->str() : hej hej med dig

ss.rdbuf() : hej med dig

But why is that? Is that because of ostreams definition of operator<str() gives me different output. In my eyes the output should be the same even if I have used getline.

Solution

ss.rdbuf()->str();

Returns copy of all buffer content.

What doing std::cout << ss.rdbuf();?

See description for

basic_ostream<charT,traits>& operator<<(basic_streambuf<charT,traits>* sb);

It read character by character from buffer and write them to ostream, until eof/fail on writing/exception occurs.

You already have read one word from buff. Now it read rest part.

Comments

[mslot]

Oh. The fact that I have'nt looked it up in one of me expensive C++ books is that Im on a vacation, so I only have google and I couldnt find a site explaining the operator<< behaviour in a way that I understood. I actually thought that getline removed tokens with the delim from the stream.

[bayda]

I didn't use one of expensive C++ books. I just undertsood that this behavior is not rbuf() specified and start looked in standard for this overloading operator<<.

[bayda]

Remove characters from reading string buffer is slow operation - and obviously don't used. Thank you for interest task:)

[mslot]

bb, looking in the standard :) I have such standard at home. I'm on a vacation and dont got it with me. I have read the declarations for the iostream operators, but that didnt tell me how it worked. I guess I was lost in google. But thanks for the link!!