Question

Basically I have a thread reading from c++ std::istream using

istream& getline ( istream& is, string& str );

And when I bind the istream with cin, then it works fine when I type the input from standard command line as the input.

But I am wondering is there a way that I can make the read thread getline get the string without
using the actual command line ?

Basically I want to achieve this:

By just calling a function WriteToIStream with parameter str (instead of type str in command line) and the read thread getilne() can get the str.

void WriteToIStream(string& str)
{
//...
}

Many Thanks

Answer 1

cin is only one instance of an input stream, bound to the standard input. For your case, you can use an istringstream (or more generally a stringstream) which is an input stream to read from a string:

std::istringstream istr("foobar");
getline(istr, some_string_variable);

This requires the standard header <sstream>.