Deleting elements from a vector

Question

The following C++ code fills a vector with a number of objects and then removes some of these objects, but it looks like it deletes the wrong ones:

vector

        

Answer 1

The proper version will look like:

for (vector::iterator i=photons.begin(); i!=photons.end(); /*note, how the advance of i is made below*/) {
   bool useless = false;

   // process photon, set useless to true for some

   // remove useless photons
   if (useless) {
     i = photons.erase(i);
   } else {
     ++i;
   }
}