Managing resources

The goal of this exercise is to get some confidence with the smart pointers provided by the C++ standard library: unique_ptr and shared_ptr.

Exercise 1

In the C language, memory is allocated with malloc and released with free. Both functions are available also in C++, possibly in namespace std. Consider c_alloc.cpp, where a bunch of memory is allocated and released with those functions. Adapt the code to manage the allocation through a smart pointer with an appropriate deleter.

Exercise 2

Open the test program dir.cpp and, following the hints in the file, complete the existing code to:

  • create a smart pointer managing a DIR resource obtained with the opendir function call
  • associate a deleter to that smart pointer
  • implement a function to read the names of the files in that directory, using readdir_r
  • check if the deleter is called at the right moment
  • hide the creation of the smart pointer behind a factory function
  • populate a vector of FILEs, properly wrapped in a smart pointer, obtained fopening the regular files in that directory

You can experiment with both kinds of smart pointers and with the type of the function arguments.