lec08-oop.md

Lec 08 - Object Oriented Programming

Overloading the << Operator

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https://mediaspace.wisc.edu/media/t/1_iqwmkd1t

Practice

Look back at the example code from the previous lecture: https://github.com/cs368-wisc/s24/blob/main/demos/lec07/houses.cpp.

Add some code so we can print coordinates with something like this:

std::cout << SOME_COORD_OBJECT << "\n";

For reference, here's the example function from the recording for printing a house:

std::ostream& operator<<(std::ostream& os, const House &obj) {
  os << "House(beds=" << obj.beds << ")";
  return os;
}

Destructors

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https://mediaspace.wisc.edu/media/t/1_xbau7tag

Practice

Add delete statements to the following as necessary so that we see A, B, and C being destroyed (don't worry about the order).

#include <iostream>

using namespace std;

class A {
public:
  ~A() {
    cout << "destroy A\n";
  }
};

class B {
public:
  ~B() {
    cout << "destroy B\n";
  }
};

class C {
  A a;
  B* b;
public:
  C(): a({}), b(new B) {}

  ~C() {
    cout << "destroy C\n";
  }
};


int main() {
  auto obj = new C;
}

Copy Constructors

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https://mediaspace.wisc.edu/media/CS%20368%20S24%20-%20Copy%20Constructor/1_da2tcqmc

Copy Assignment Operators

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https://mediaspace.wisc.edu/media/t/1_ykeqa0lr

Assignment Style

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https://mediaspace.wisc.edu/media/t/1_3zdyg7fo

Practice

The C++ vector type has MANY overloaded constructors: https://en.cppreference.com/w/cpp/container/vector/vector.

The following code uses a constructor that takes a initializer_list, and the result is a vector containing one number, which is 10.

#include <iostream>
#include <vector>

using namespace std;

int main() {
  vector<int> nums{10};
  cout << "there are " << nums.size() << " numbers\n";
}

Modify the initialization style for nums so that we instead get a vector of 10 numbers.