Using operator[] on empty std::vector

Question

I was advised a while ago that is was common place to use std::vector as exception safe dynamic array in c++ rather than allocating raw arrays... for exampl

Answer 1

If you want to get cleaner behaviour in this scenario you could replace use of a[0] with use a.at(0), which will throw if the index is invalid.

A pragmatic solution would be to init vector with n+1 entries and constrain access to 0..n-1 (as this code already does).

void foo (int n) {
   std::vector scoped_array (n+1);
   char* pointer = &scoped_array[0];
   file.read ( pointer , n );
   for (int i = 0; i < n; ++i) {
  //do something
   }
}