Exercises

1.

This exercises makes use of the Point class created in the previous chapter. See Listing 17.6.1 for the code for it.

A Segment should connect two points (its endpoints). When we make a segment, we will give the constructor the addresses of two Points - we want the segment to use those points as its endpoints. The segment should link to those points, not make copies of them. (Aggregation)

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Finish the Segment class by:

Adding the member variables m_p1 and m_p2 needed to hold the addresses of two Points.

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Make a constructor that accepts two memory addresses to store.

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2.

This exercises makes use of the Point class created in the previous chapter. See Listing 17.6.1 for the code for it.

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This exercises builds on Exercise 18.15.1 - begin by copying your code for the member variables and constructors into this problem.

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Then add code for a shift(int deltaX, int deltaY) function to Segment so that we can shift the segment by some amount in x (deltaX) and some amount in y (deltaY). Moving a segment should move both of its endpoints.

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Hint.

Your Segment class does not have access to the private data of Point. You will need to use Point functions to modify the two endpoints.

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3.

Below is a very simple implementation of a Friend class. In the TEST_CASE, add code to create a Friend f1 named Ronnie, a Friend named Dakota, and a friend named Mary. Make Ronnie Friends with Dakota, Dakota friends with Mary, and Mary friends with Ronnie. Note that friendship is only set in one direction in this program.

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#include <iostream>
#include <string>
#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest.h"

import Point;

using namespace std;

class Friend {
private:
    Friend* m_bestFriend = nullptr;
    string m_name;

public:
    Friend(string name) {
        m_name = name;
    }

Friend* getFriend() {
        return m_bestFriend;
    }

void setFriend(Friend* bestFriend) {
        m_bestFriend = bestFriend;
    }

string getName() {
        return m_name;
    }
};

TEST_CASE("Friend setup") {
^^^!

// your setup here
===!
    string f1Name = f1.getName();
    CHECK(f1Name == "Ronnie");

// f1 is an object, so we can call getFriend directly
    // the pointer that is returned is a Person*, so we must then use -> to call getName
    string f2Name = f1.getFriend()->getName();
    CHECK(f2Name == "Dakota");

string f3Name = f1.getFriend()->getFriend()->getName();
    CHECK(f3Name == "Mary");

string f4Name = f1.getFriend()->getFriend()->getFriend()->getName();
    CHECK(f4Name == "Ronnie");
}

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4.

Add a bool bestieCheck() function to the Friend class. If a Friend’s m_bestFriend is a null pointer return false. If they have a m_bestFriend, check to see if their best friend’s m_bestFriend is the current object (this), if so return true, otherwise return false. In other words, your function returns true if the Friend and their best friend agree that they are best friends. Otherwise it returns false.

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#include <iostream>
#include <string>
#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest.h"

import Point;

using namespace std;

class Friend {
private:
    Friend* m_bestFriend;
    string m_name;

public:
    Friend(string name, Friend* bestFriend = nullptr) {
        m_name = name;
        m_bestFriend = bestFriend;
    }

Friend* getFriend() {
        return m_bestFriend;
    }

void setFriend(Friend* bestFriend) {
        m_bestFriend = bestFriend;
    }

string getName() {
        return m_name;
    }

^^^!

// your bestieCheck function here
===!
};  // end of Friend class

TEST_CASE("bestieCheck no friend") {
    Friend f1("Bob", nullptr);
    bool isBesties = f1.bestieCheck();
    CHECK(isBesties == false);
}

TEST_CASE("bestieCheck agree") {
    Friend f1("Duncan", nullptr);
    Friend f2("Shannon", &f1);
    f1.setFriend(&f2);

bool duncanIsBestie = f1.bestieCheck();
    CHECK(duncanIsBestie == true);

bool shannonIsBestie = f2.bestieCheck();
    CHECK(shannonIsBestie == true);
}

TEST_CASE("bestieCheck disagree") {
    Friend f1("Duncan", nullptr);
    Friend f2("Shannon", &f1);
    Friend f3("Doug", &f2);
    f1.setFriend(&f3);

// No, Doug is not a bestie of Duncan
    bool duncanIsBestie = f1.bestieCheck();
    CHECK(duncanIsBestie == false);

// No, Duncan is not a bestie of Shannon
    bool shannonIsBestie = f2.bestieCheck();
    CHECK(shannonIsBestie == false);
}

TEST_CASE("bestieCheck self") {
    Friend f1("Bob", nullptr);
    f1.setFriend(&f1); // Bob is his own bestie
    bool isBesties = f1.bestieCheck();
    CHECK(isBesties == true);
}

Hint 1.

You will need to compare the best friend’s best friend to this.

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Hint 2.

You should check if the current object has a best friend before you try to access best friend’s best friend variable.

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Welcome to Programming and Data Structures

Exercises 18.15 Exercises

1.

2.

3.

4.