Streaming into `char` array with `ostream` - how to get characters written count?-CodePudding

This answer shows how to write to an array with stringstream, but can we obtain the total number of characters written? Surely the stringstream has some information to know where to put the next character, but I don't know how to access it.

The OP of the linked question even asks this in a comment but I wanted a separate question to be sure.

I know ostrstream has a pcount method, unfortunately, it is deprecated.

CodePudding user response：

The std::ostrstream class itself is deprecated.

Use std::ostringstream instead, which has a tellp() method.

#include <sstream>

int main()
{
    char buf[1024];
    std::ostringstream stream;

    stream.rdbuf()->pubsetbuf(buf, sizeof(buf));

    auto start = stream.tellp();
    stream << "Hello " << "World " << std::endl;
    auto written = stream.tellp() - start;

    //...
}