Exercises

Checkpoint 22.16.1.

Write a function getPI that allocates a double on the heap, initializes the memory (or assigns it) to hold 3.14, and returns a pointer to the allocated memory.

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Checkpoint 22.16.2.

Write a function makeArray that allocates an array of 3 double on the heap, sets them to 1.1, 2.2, and 3.3, then returns a pointer to the array.

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Hint.

You can use {value, value, value} to initialize the array. Or you can do assignments to the three elements after creating it.

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Checkpoint 22.16.3.

Write a function makeBigArray that allocates an array of 100 double on the heap and sets them all to 5.0. It should then return a pointer to the array.

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Hint.

You will almost certainly need a loop to set all the elements of the array.

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Checkpoint 22.16.4.

The class NumberWrapper manages an array of two integer values on the heap. (Which is admittedly a kind of silly thing to do.)

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Implement the copy constructor for NumberWrapper. It is declared inside the class, you will implement it outside the class (at line 42). It should make a deep copy of the managed memory.

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#include <iostream>
using namespace std;

class NumberWrapper {
public:
    NumberWrapper(int num1, int num2);
    void setNum(int position, int value);
    int getNumOne() const;
    int getNumTwo() const;
    ~NumberWrapper();

NumberWrapper(const NumberWrapper& other);
    NumberWrapper& operator=(const NumberWrapper& other);

private:
    int* m_myAddress; // Memory address of array
};

NumberWrapper::NumberWrapper(int num1, int num2) {
    m_myAddress = new int[2];
    m_myAddress[0] = num1;
    m_myAddress[1] = num2;
}

void NumberWrapper::setNum(int position, int value) {
    m_myAddress[position] = value;
}

int NumberWrapper::getNumOne() const {
    return m_myAddress[0];
}

int NumberWrapper::getNumTwo() const {
    return m_myAddress[1];
}

NumberWrapper::~NumberWrapper() {
    delete[] m_myAddress;
}

^^^!

//YOUR CODE HERE
===!

#define DOCTEST_CONFIG_IMPLEMENT_WITH_MAIN
#include "doctest.h"

TEST_CASE("copyConstructor") {
    NumberWrapper original(6, 7);
    NumberWrapper copy(original);

CHECK(copy.getNumOne() == 6);
    CHECK(copy.getNumTwo() == 7);
    
    copy.setNum(0,100);
    CHECK(original.getNumOne() == 6); // Original should remain unchanged
    CHECK(original.getNumTwo() == 7);
    CHECK(copy.getNumOne() == 100); // Copy should reflect the change
}

Hint.

Make sure to do a deep copy. Allocate your own array and then copy the values one by one from the original.

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Checkpoint 22.16.5.

The class NumberWrapper manages an array of two integer values on the heap. (Which is admittedly a kind of silly thing to do.)

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Implement the assignment operator NumberWrapper. It is declared inside the class, you will implement it outside the class (at line 42). It should make a deep copy of the managed memory.

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Don’t forget to check for self-assignment! If you have a use after free error, it could be due to not handling self-assignment correctly.