What are the "string", "stream" and "stringstream" classes in C++?

Question

I want to know what's the difference between string and stream in c++, and what's stringstream?

Answer 1

• istream and ostream: interfaces to streaming data (files, sockets, etc.)
• istringstream: an istream that wraps a string and offers its contents
• ostringstream: an ostream that saves the content written to it as a string

Example:

istringstream datastream("1 2 3");

int val;
datastream >> val;
cout << val << endl; // prints 1

datastream >> val;
cout << val << endl; // prints 2

datastream >> val;
cout << val << endl; // prints 3


ostringstream outstream;
outstream << 1 << "+" << 2 << "=" << 3;
cout << outstream.str() << endl; // prints "1+2=3"

Answer 2

Very Informally: A string is a collection of characters, a stream is a tool to manipulate moving data around. A string stream is a c++ class that lets you use a string as the source and destination of data for a stream.