C++ London Uni RAII exercise

This repository contains a simple example of handling resources in C++.

The supplied memory_resource.hpp file provides the following functions:

• MemoryResource acquire_resource(int size);

  Returns a MemoryResource object consisting of an array of size ints

• void release_resource(MemoryResource& resource);

  Destroys a MemoryResource previously acquired by acquire_resource()

• int access_resource(const MemoryResource& resource, int index);

  Returns the value at position index in the MemoryResource array

(Many C libraries provide APIs like this.)

The starter code in main.cpp uses the above functions to calculate the sum of the values in a MemoryResource of a given size; however, if the total is too small (less than 100), it returns zero instead.

Exercise 1

Unfortunately, the use_resource_example() function in main.cpp has a bug! Can you spot what it is?

This bug can be avoided by properly using RAII

• Write a new class ResourceHandle which manages a MemoryResource by automatically calling acquire_resource() when it is created, and release_resource() when it is destroyed

• Add a member function to ResourceHandle which allows you to access the resource using access_resource()

• Use this class to fix the bug in use_resource_example()

Exercise 2

What happens when you create a copy of a ResourceHandle object? Why?

• Update your ResourceHandle class to use the suppled function copy_resource() as appropriate to solve this problem