How to read entire stream into a std::string?

c++ string stream
Roddy picture Roddy · Jul 8, 2010 · Viewed 61.1k times · Source

I'm trying to read an entire stream (multiple lines) into a string.

I'm using this code, and it works, but it's offending my sense of style... Surely there's an easier way? Maybe using stringstreams?

void Obj::loadFromStream(std::istream & stream)
{ 
  std::string s;

  std::streampos p = stream.tellg();  // remember where we are

  stream.seekg(0, std::ios_base::end); // go to the end
  std::streamoff sz = stream.tellg() - p;  // work out the size
  stream.seekg(p);        // restore the position

  s.resize(sz);          // resize the string
  stream.read(&s[0], sz);  // and finally, read in the data.

Actually, a const reference to a string would do as well, and that may make things easier...

const std::string &s(... a miracle occurs here...)

Answer

Cubbi picture Cubbi · Jul 8, 2010

How about 

std::istreambuf_iterator<char> eos;
std::string s(std::istreambuf_iterator<char>(stream), eos);

(could be a one-liner if not for MVP)

post-2011 edit, this approach is now spelled

std::string s(std::istreambuf_iterator<char>(stream), {});

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