while ( a >> b) ?

[wasabi]

I am debugging a friend's code and don't understand the following statement:

while( (istringstream) ss >> (int) numOfElems )
      std::cout<< "..numOfElem = " << numOfElems << std::endl;

The casts were placed there for reference.

What I don't understand is: what does that while() statement mean? When will [code
ss >> numofElems[/code] be false? Does that mean "should the first thing in ss not be an integer, try again until it is?" After all, operator>> returns *this, which will always point to a memory slot, no? Or does *this==NULL once the istringstream runs off its associated string?

[Zhuge]

It returns an istringstream, yes. Putting that into a boolean check will return, basically, istringstream.good(). So will keep reading into numOfElems until you hit end of file or an error occurs, since good() will return false at that point.

[firedraco]

Btw, you probably shouldn't include the types like that, since as it is it looks like you are trying to cast numOfElems to a int, which makes no sense in this situation. Just put them in a separate code (or preferably, put it in a comment block).