CSE 333 Exercise 14

• Learn how to use C++ smart pointers to handle heap memory resource management.

Consider the following C++ file, named ex14.cc: (to download: right-click the link, then left-click "Save link as...")

/*
 * Copyright ©2026 Justin Hsia and Amber Hu. All rights reserved.
 * Permission is hereby granted to students registered for University of
 * Washington CSE 333 for use solely during Winter Quarter 2026 for
 * purposes of the course. No other use, copying, distribution, or
 * modification is permitted without prior written consent. Copyrights
 * for third-party components of this work must be honored. Instructors
 * interested in reusing these course materials should contact the
 * authors.
 */

#include <algorithm>
#include <cstdlib>
#include <iostream>
#include <vector>

int main(int argc, char** argv) {
  // Allocate an integer on the heap, initialize to value 5.
  int* x = new int(5);
  std::cout << "*x is: " << *x << std::endl;

  // Allocate a vector of integers on the heap, add some values to
  // that vector, sort the vector, print the values.
  std::vector<int>* v = new std::vector<int>;
  v->push_back(13);
  v->push_back(42);
  v->push_back(17);
  std::sort(v->begin(), v->end());
  std::cout << "sorted v: ";
  for (int& el : *v) {
    std::cout << el << " ";
  }
  std::cout << std::endl;

  // Allocate a vector of (integer pointers) on the stack, add some
  // values to the vector from the heap, print the values.
  std::vector<int*> v2;
  v2.push_back(new int(13));
  v2.push_back(new int(42));
  v2.push_back(new int(17));
  std::cout << "unsorted v2: ";
  for (int* el : v2) {
    std::cout << *el << " ";
  }
  std::cout << std::endl;

  return EXIT_SUCCESS;
}

If you try compiling and running this program under valgrind, you'll notice that there are several memory leaks in it, all arising from allocating values on the heap using new but not deallocating them. Your challenge is to fix these memory leaks.

However, to make it interesting, you are not allowed to directly use delete (or free, which would be a mistake, of course). Instead, you have to modify the code to use the std::unique_ptr smart pointer. So, for example, line 19 of the program allocates an integer on the heap using new. You will need to modify that line to transfer ownership of the allocated integer to a std::unique_ptr<int>.

Along with the modifications you make, please change the comment at the top of the file to include your name and CSE or UW email address.

Smart Pointer Types

We discussed multiple kinds of smart pointers in lecture, and they all have different use cases and behaviors, so think carefully about which type you want to use. In particular, think about what kind of ownership makes the most sense for your changes, as you should use the "best-fit" even if another type might also work.

Submit the following file(s) by creating an ex14-submit tag in your exercise repo before the assignment deadline. The file(s) should be located in the exact directory listed below, including capitalization:

• ex14/ex14.cc

Your code must:

• Compile without errors or warnings on CSE Linux machines (lab workstations, attu, or CSE home VM).
• Have no runtime errors, memory leaks, or memory errors (g++ and valgrind).
• Be contained in the file listed above that compiles with the command:
  

  $ g++ -Wall -g -std=c++17 -o ex14 ex14.cc

• Have a comment at the top of your .cc and .h files with your name(s) and CSE or UW email address(es).
• Be pretty: the formatting, modularization, variable and function names, commenting, and so on should be consistent with class style guidelines. Additionally, the linter shouldn't have any complaints about your code (cpplint.py).
• Be robust: your code should deal with hard-to-handle/edge cases and bogus user input (if there are any) gracefully.