c++ istream轉換爲std::string

----------------------------------------------------------------------------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), {});

I'm late to the party, but here is a fairly efficient solution:

std::string gulp(std::istream &in) { std::string ret; char buffer[4096]; while (in.read(buffer, sizeof(buffer))) ret.append(buffer, sizeof(buffer)); ret.append(buffer, in.gcount()); return ret; }

I did some benchmarking, and it turns out that the std::istreambuf_iterator technique (used by the accepted answer) is actually much slower. On gcc 4.4.5 with -O3, it's about a 4.5x difference on my machine, and the gap becomes wider with lower optimization settings.

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You can try using something from algorithms. I have to get ready for work but here's a very quick stab at things (there's got to be a better way):

copy( istreambuf_iterator<char>(stream), istreambuf_iterator<char>(), back_inserter(s) );
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You could do

std::string s; std::ostringstream os; os<<stream.rdbuf(); s=os.str();

but I don't know if it's more efficient.

Alternative version:

std::string s; std::ostringstream os; stream>>os.rdbuf(); s=os.str();

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Well, if you are looking for a simple and 'readable' way to do it. I would recomend add/use some high level framework on your project. For that I's always use Poco and Boost on all my projects. In this case, with Poco:

 string text; FileStream fstream(TEXT_FILE_PATH); StreamCopier::copyToString(fstream, text);

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Perhaps this 1 line C++11 solution:

std::vector<char> s{std::istreambuf_iterator<char>{in},{}};