[w7] Added exercise descriptions and solutions

12 files changed, 778 insertions, 0 deletions

diff --git a/week07/Exercise1.cpp b/week07/Exercise1.cpp
new file mode 100644
index 0000000..ec2a47a
--- /dev/null
+++ b/week07/Exercise1.cpp
@@ -0,0 +1,87 @@
+#include "Exercise1.h"
+#include <cstring>
+
+/* Private */
+
+void Recipe::resize() {
+	allocated *= 2;
+	Ingredient* moreIngredients = new Ingredient[allocated];
+	for (int i = 0; i < lastIndex; i++) {
+		moreIngredients[i] = ingredients[i];
+	}
+	delete[] ingredients;
+	ingredients = moreIngredients;
+}
+
+void Recipe::free() {
+	delete[] ingredients;
+}
+void Recipe::copyFrom(const Recipe& other) {
+	this->lastIndex = other.lastIndex;
+	this->allocated = other.allocated;
+	this->ingredients = new Ingredient[allocated];
+	for (int i = 0; i < lastIndex; i++) {
+		this->ingredients[i] = other.ingredients[i];
+	}
+}
+
+/* Public */
+
+Recipe::Recipe() {
+	ingredients = nullptr;
+	lastIndex = allocated = 0;
+}
+Recipe::~Recipe() {
+	free();
+}
+Recipe::Recipe(const Recipe& other) {
+	copyFrom(other);
+}
+Recipe& Recipe::operator=(const Recipe& other) {
+	if (this != &other) {
+		free();
+		copyFrom(other);
+	}
+	return *this;
+}
+Recipe::Recipe(Recipe&& other) {
+	this->ingredients = other.ingredients;
+	this->lastIndex = other.lastIndex;
+	this->allocated = other.allocated;
+
+	other.ingredients = nullptr;
+}
+Recipe& Recipe::operator=(Recipe&& other) {
+	if (this != &other) {
+		free();
+
+		this->ingredients = other.ingredients;
+		this->lastIndex = other.lastIndex;
+		this->allocated = other.allocated;
+
+		other.ingredients = nullptr;
+	}
+	return *this;
+}
+
+void Recipe::AddIngredient(const Ingredient& newIng) {
+	if (lastIndex == allocated) {
+		resize();
+	}
+	ingredients[lastIndex++] = newIng;
+}
+void Recipe::RemoveIngredient(const char* name) {
+	int index = 0;
+	while (index < lastIndex && strcmp(ingredients[index].name, name) != 0) {
+		index++;
+	}
+	if (index == lastIndex) {
+		return;
+	}
+
+	while (index < lastIndex) {
+		ingredients[index] = ingredients[index+1];
+		index++;
+	}
+	lastIndex--;
+}
diff --git a/week07/Exercise1.h b/week07/Exercise1.h
new file mode 100644
index 0000000..6de1a09
--- /dev/null
+++ b/week07/Exercise1.h
@@ -0,0 +1,25 @@
+struct Ingredient {
+	char name[512];
+	float amount;
+};
+
+class Recipe {
+	Ingredient* ingredients;
+	unsigned lastIndex;
+	unsigned allocated;
+
+	void resize();
+	void free();
+	void copyFrom(const Recipe& other);
+
+public:
+	Recipe();
+	~Recipe();
+	Recipe(const Recipe& other);
+	Recipe& operator=(const Recipe& other);
+	Recipe(Recipe&& other);
+	Recipe& operator=(Recipe&& other);
+
+	void AddIngredient(const Ingredient& newIng);
+	void RemoveIngredient(const char* name);
+};
diff --git a/week07/Exercise2.cpp b/week07/Exercise2.cpp
new file mode 100644
index 0000000..2ec31d5
--- /dev/null
+++ b/week07/Exercise2.cpp
@@ -0,0 +1,24 @@
+#include <fstream>
+#include <iostream>
+
+int main() {
+	char fileName[1024];
+	std::cin.getline(fileName, 1024);
+
+	std::ifstream file(fileName);
+	if (!file.is_open()) {
+		std::cout << "Couldn't open file!" << std::endl;
+		return -1;
+	}
+
+	file.seekg(0, std::ios::end);
+	int third = file.tellg() / 3;
+	file.seekg(2 * third - 1, std::ios::beg);
+
+	while (third <= file.tellg()) {
+		std::cout << (char)file.peek();
+		file.seekg(-1, std::ios::cur);
+	}
+
+	file.close();
+}
diff --git a/week07/Exercise3.cpp b/week07/Exercise3.cpp
new file mode 100644
index 0000000..3137ddd
--- /dev/null
+++ b/week07/Exercise3.cpp
@@ -0,0 +1,77 @@
+#include "Exercise3.h"
+#include <fstream>
+#include <iostream>
+
+/* Public */
+
+Thermometer::Thermometer(unsigned maxMeasurable, unsigned minMeasurable, unsigned currentTemperature) {
+	this->maxMeasurable = maxMeasurable;
+	this->minMeasurable = minMeasurable;
+	this->currentTemperature = currentTemperature;
+}
+
+void Thermometer::Print() {
+	std::cout << maxMeasurable << " " << minMeasurable << " " << currentTemperature << std::endl;
+}
+
+void Thermometer::SaveText(const char* fileName) {
+	std::ofstream outFile(fileName);
+	if (!outFile.is_open()) {
+		return;
+	}
+
+	outFile << maxMeasurable << "," << minMeasurable << "," << currentTemperature;
+	outFile.close();
+}
+void Thermometer::LoadText(const char* fileName) {
+	std::ifstream inFile(fileName);
+	if (!inFile.is_open()) {
+		return;
+	}
+
+	inFile >> maxMeasurable;
+	inFile.ignore();
+	inFile >> minMeasurable;
+	inFile.ignore();
+	inFile >> currentTemperature;
+	inFile.close();
+}
+
+void Thermometer::SaveBinary(const char* fileName) {
+	std::ofstream outFile(fileName, std::ios::binary);
+	if (!outFile.is_open()) {
+		return;
+	}
+
+	outFile.write((const char*)&maxMeasurable, sizeof(maxMeasurable));
+	outFile.write((const char*)&minMeasurable, sizeof(minMeasurable));
+	outFile.write((const char*)&currentTemperature, sizeof(currentTemperature));
+	outFile.close();
+}
+void Thermometer::LoadBinary(const char* fileName) {
+	std::ifstream inFile(fileName, std::ios::binary);
+	if (!inFile.is_open()) {
+		return;
+	}
+
+	inFile.read((char*)&maxMeasurable, sizeof(maxMeasurable));
+	inFile.read((char*)&minMeasurable, sizeof(minMeasurable));
+	inFile.read((char*)&currentTemperature, sizeof(currentTemperature));
+	inFile.close();
+}
+
+int main() {
+	Thermometer t1(100, 0, 20);
+	t1.SaveText("t1.txt");
+
+	Thermometer t2(50, 20, 36);
+	t2.SaveBinary("t2.dat");
+
+	Thermometer t3(5, 5, 5);
+
+	t3.LoadText("t1.txt");
+	t3.Print();
+
+	t3.LoadBinary("t2.dat");
+	t3.Print();
+}
diff --git a/week07/Exercise3.h b/week07/Exercise3.h
new file mode 100644
index 0000000..2cf27bf
--- /dev/null
+++ b/week07/Exercise3.h
@@ -0,0 +1,15 @@
+class Thermometer {
+	unsigned maxMeasurable;
+	unsigned minMeasurable;
+	unsigned currentTemperature;
+
+public:
+	Thermometer(unsigned maxMeasurable, unsigned minMeasurable, unsigned currentTemperature);
+	void Print();
+
+	void SaveText(const char* fileName);
+	void LoadText(const char* fileName);
+
+	void SaveBinary(const char* fileName);
+	void LoadBinary(const char* fileName);
+};
diff --git a/week07/Exercise4.cpp b/week07/Exercise4.cpp
new file mode 100644
index 0000000..50eb587
--- /dev/null
+++ b/week07/Exercise4.cpp
@@ -0,0 +1,139 @@
+#include "Exercise4.h"
+#include <fstream>
+#include <iostream>
+#include <cstring>
+
+/* Private */
+
+void Street::free() {
+	delete[] name;
+}
+void Street::copyFrom(const Street& other) {
+	this->number = other.number;
+	this->name = new char[strlen(other.name)+1];
+	strcpy(this->name, other.name);
+}
+
+/* Public */
+
+Street::Street(const char* name, int number) {
+	this->number = number;
+	this->name = new char[strlen(name)+1];
+	strcpy(this->name, name);
+}
+
+void Street::Print() {
+	std::cout << name << " " << number << std::endl;
+}
+
+Street::Street() {
+	this->name = nullptr;
+	this->number = 0;
+}
+Street::~Street() {
+	free();
+}
+Street::Street(const Street& other) {
+	copyFrom(other);
+}
+Street& Street::operator=(const Street& other) {
+	if (this != &other) {
+		free();
+		copyFrom(other);
+	}
+	return *this;
+}
+Street::Street(Street&& other) {
+	this->name = other.name;
+	this->number = other.number;
+
+	other.name = nullptr;
+}
+Street& Street::operator=(Street&& other) {
+	if (this != &other) {
+		free();
+
+		this->name = other.name;
+		this->number = other.number;
+
+		other.name = nullptr;
+	}
+	return *this;
+}
+
+void Street::SaveText(const char* fileName) {
+	std::ofstream outFile(fileName);
+	if (!outFile.is_open()) {
+		return;
+	}
+
+	outFile << number << ',' << name;
+	outFile.close();
+}
+void Street::LoadText(const char* fileName) {
+	std::ifstream inFile(fileName);
+	if (!inFile.is_open()) {
+		return;
+	}
+
+	free();
+
+	inFile >> number;
+	inFile.ignore();
+
+	unsigned nameStart = inFile.tellg();
+	inFile.seekg(0, std::ios::end);
+	unsigned nameLen = (unsigned)inFile.tellg() - nameStart + 1;
+	inFile.seekg(nameStart, std::ios::beg);
+
+	name = new char[nameLen+1];
+	inFile.get(name, nameLen);
+	name[nameLen] = '\0';
+
+	inFile.close();
+}
+
+void Street::SaveBinary(const char* fileName) {
+	std::ofstream outFile(fileName, std::ios::binary);
+	if (!outFile.is_open()) {
+		return;
+	}
+
+	outFile.write((const char*)&number, sizeof(number));
+	outFile.write(name, sizeof(char) * (strlen(name)+1));
+
+	outFile.close();
+}
+void Street::LoadBinary(const char* fileName) {
+	std::ifstream inFile(fileName, std::ios::binary);
+	if (!inFile.is_open()) {
+		return;
+	}
+
+	inFile.seekg(0, std::ios::end);
+	unsigned nameLen = (unsigned)inFile.tellg() - sizeof(number);
+	inFile.seekg(0, std::ios::beg);
+
+	free();
+
+	inFile.read((char*)&number, sizeof(number));
+	name = new char[nameLen];
+	inFile.read(name, nameLen);
+
+	inFile.close();
+}
+
+int main() {
+	Street s1("Hollywood Blvd", 13);
+	s1.SaveText("s1.txt");
+
+	Street s2("Djeims Baucher", 5);
+	s2.SaveBinary("s2.dat");
+
+	Street s3;
+	s3.LoadText("s1.txt");
+	s3.Print();
+
+	s3.LoadBinary("s2.dat");
+	s3.Print();
+}
diff --git a/week07/Exercise4.h b/week07/Exercise4.h
new file mode 100644
index 0000000..c5dc5c9
--- /dev/null
+++ b/week07/Exercise4.h
@@ -0,0 +1,24 @@
+class Street {
+	char* name;
+	int number;
+
+	void free();
+	void copyFrom(const Street& other);
+
+public:
+	Street(const char* name, int number);
+	void Print();
+
+	Street();
+	~Street();
+	Street(const Street& other);
+	Street& operator=(const Street& other);
+	Street(Street&& other);
+	Street& operator=(Street&& other);
+
+	void SaveText(const char* fileName);
+	void LoadText(const char* fileName);
+
+	void SaveBinary(const char* fileName);
+	void LoadBinary(const char* fileName);
+};
diff --git a/week07/Exercise5.cpp b/week07/Exercise5.cpp
new file mode 100644
index 0000000..8187771
--- /dev/null
+++ b/week07/Exercise5.cpp
@@ -0,0 +1,180 @@
+#include "Exercise5.h"
+#include <fstream>
+#include <iostream>
+#include <cstring>
+
+/* Private */
+
+void TransportTicket::free() {
+	delete[] source;
+	delete[] destination;
+}
+void TransportTicket::copyFrom(const TransportTicket& other) {
+	this->id = other.id;
+	this->source = new char[strlen(other.source)+1];
+	strcpy(this->source, other.source);
+	this->destination = new char[strlen(other.destination)+1];
+	strcpy(this->destination, other.destination);
+	this->price = other.price;
+}
+
+/* Public */
+
+TransportTicket::TransportTicket(unsigned id, const char* source, const char* destination, float price) {
+	this->id = id;
+	this->source = new char[strlen(source)+1];
+	strcpy(this->source, source);
+	this->destination = new char[strlen(destination)+1];
+	strcpy(this->destination, destination);
+	this->price = price;
+}
+void TransportTicket::Print() {
+	std::cout << id << " " << source << " " << destination << " " << price << std::endl;
+}
+
+TransportTicket::TransportTicket() {
+	id = price = 0;
+	source = destination = nullptr;
+}
+TransportTicket::~TransportTicket() {
+	free();
+}
+TransportTicket::TransportTicket(const TransportTicket& other) {
+	copyFrom(other);
+}
+TransportTicket& TransportTicket::operator=(const TransportTicket& other) {
+	if (this != &other) {
+		free();
+		copyFrom(other);
+	}
+	return *this;
+}
+TransportTicket::TransportTicket(TransportTicket&& other) {
+	this->id = other.id;
+	this->source = other.source;
+	this->destination = other.destination;
+	this->price = other.price;
+
+	other.source = nullptr;
+	other.destination = nullptr;
+}
+TransportTicket& TransportTicket::operator=(TransportTicket&& other) {
+	if (this != &other) {
+		free();
+
+		this->id = other.id;
+		this->source = other.source;
+		this->destination = other.destination;
+		this->price = other.price;
+
+		other.destination = nullptr;
+		other.source = nullptr;
+	}
+	return *this;
+}
+
+void TransportTicket::SaveText(const char* fileName) {
+	std::ofstream outFile(fileName);
+	if (!outFile.is_open()) {
+		return;
+	}
+
+	outFile << id << ',' << source << ',' << destination << ',' << price;
+	outFile.close();
+}
+
+unsigned distanceUntilComma(std::ifstream& inFile) {
+	unsigned start = inFile.tellg();
+	while (inFile.peek() != ',') {
+		inFile.get();
+	}
+	unsigned len = (unsigned)inFile.tellg() - start + 1;
+	inFile.seekg(start, std::ios::beg);
+	return len;
+}
+void TransportTicket::LoadText(const char* fileName) {
+	std::ifstream inFile(fileName);
+	if (!inFile.is_open()) {
+		return;
+	}
+
+	free();
+
+	inFile >> id;
+	inFile.ignore();
+
+	unsigned sourceLen = distanceUntilComma(inFile);
+	source = new char[sourceLen+1];
+	inFile.get(source, sourceLen);
+	source[sourceLen] = '\0';
+
+	inFile.ignore();
+
+	unsigned destinationLen = distanceUntilComma(inFile);
+	destination = new char[destinationLen+1];
+	inFile.get(destination, destinationLen);
+	destination[destinationLen] = '\0';
+
+	inFile.ignore();
+	inFile >> price;
+
+	inFile.close();
+}
+
+void TransportTicket::SaveBinary(const char* fileName) {
+	std::ofstream outFile(fileName, std::ios::binary);
+	if (!outFile.is_open()) {
+		return;
+	}
+
+	outFile.write((const char*)&id, sizeof(id));
+	outFile.write((const char*)&price, sizeof(price));
+
+	unsigned sourceLen = strlen(source)+1;
+	outFile.write((const char*)&sourceLen, sizeof(sourceLen));
+	outFile.write(source, sizeof(char) * sourceLen);
+
+	unsigned destinationLen = strlen(destination)+1;
+	outFile.write((const char*)&destinationLen, sizeof(destinationLen));
+	outFile.write(destination, sizeof(char) * destinationLen);
+
+	outFile.close();
+}
+void TransportTicket::LoadBinary(const char* fileName) {
+	std::ifstream inFile(fileName, std::ios::binary);
+	if (!inFile.is_open()) {
+		return;
+	}
+
+	free();
+
+	inFile.read((char*)&id, sizeof(id));
+	inFile.read((char*)&price, sizeof(price));
+
+	unsigned sourceLen = 0;
+	inFile.read((char*)&sourceLen, sizeof(sourceLen));
+	source = new char[sourceLen+1];
+	inFile.read(source, sizeof(char) * sourceLen);
+
+	unsigned destinationLen = 0;
+	inFile.read((char*)&destinationLen, sizeof(destinationLen));
+	destination = new char[destinationLen+1];
+	inFile.read(destination, sizeof(char) * destinationLen);
+
+	inFile.close();
+}
+
+int main() {
+	TransportTicket t1(193, "Sofia", "Bourgas", 15.50);
+	t1.SaveText("t1.txt");
+
+	TransportTicket t2(782, "Sofia", "Plovdiv", 8.99);
+	t2.SaveBinary("t2.dat");
+
+	TransportTicket t3;
+	t3.LoadText("t1.txt");
+	t3.Print();
+
+	t3.LoadBinary("t2.dat");
+	t3.Print();
+}
diff --git a/week07/Exercise5.h b/week07/Exercise5.h
new file mode 100644
index 0000000..f588efa
--- /dev/null
+++ b/week07/Exercise5.h
@@ -0,0 +1,26 @@
+class TransportTicket {
+	unsigned id;
+	char* source;
+	char* destination;
+	float price;
+
+	void free();
+	void copyFrom(const TransportTicket& other);
+
+public:
+	TransportTicket(unsigned id, const char* source, const char* destination, float price);
+	void Print();
+
+	TransportTicket();
+	~TransportTicket();
+	TransportTicket(const TransportTicket& other);
+	TransportTicket& operator=(const TransportTicket& other);
+	TransportTicket(TransportTicket&& other);
+	TransportTicket& operator=(TransportTicket&& other);
+
+	void SaveText(const char* fileName);
+	void LoadText(const char* fileName);
+
+	void SaveBinary(const char* fileName);
+	void LoadBinary(const char* fileName);
+};
diff --git a/week07/Exercise6.cpp b/week07/Exercise6.cpp
new file mode 100644
index 0000000..200f4d8
--- /dev/null
+++ b/week07/Exercise6.cpp
@@ -0,0 +1,83 @@
+#include "Exercise6.h"
+#include <iostream>
+
+/* Private */
+
+void Matrix::addBy(int amount) {
+	for (int i = 0; i < 4; i++) {
+		values[i] += amount;
+	}
+}
+
+/* Public */
+
+Matrix::Matrix(int a, int b, int c, int d) {
+	values[0] = a;
+	values[1] = b;
+	values[2] = c;
+	values[3] = d;
+}
+
+Matrix& Matrix::operator++() { // ++matrix
+	addBy(+1);
+	return *this;
+}
+Matrix Matrix::operator++(int) { // matrix++
+	Matrix copy = *this;
+	addBy(+1);
+	return copy;
+}
+Matrix& Matrix::operator--() { // --matrix
+	addBy(-1);
+	return *this;
+}
+Matrix Matrix::operator--(int) { // matrix--
+	Matrix copy = *this;
+	addBy(-1);
+	return copy;
+}
+
+Matrix& Matrix::operator+=(const Matrix& rhs) {
+	for (int i = 0; i < 4; i++) {
+		values[i] += rhs.values[i];
+	}
+	return *this;
+}
+Matrix& Matrix::operator-=(const Matrix& rhs) {
+	for (int i = 0; i < 4; i++) {
+		values[i] -= rhs.values[i];
+	}
+	return *this;
+}
+Matrix& Matrix::operator*=(const Matrix& rhs) {
+	values[0] = values[0] * rhs.values[0] + values[1] * rhs.values[2];
+	values[1] = values[0] * rhs.values[1] + values[1] * rhs.values[3];
+	values[2] = values[2] * rhs.values[0] + values[3] * rhs.values[2];
+	values[3] = values[2] * rhs.values[1] + values[3] * rhs.values[3];
+	return *this;
+}
+
+/* Friend */
+
+Matrix operator+(const Matrix& lhs, const Matrix& rhs) {
+	Matrix ret = lhs;
+	ret += rhs;
+	return ret;
+}
+Matrix operator-(const Matrix& lhs, const Matrix& rhs) {
+	Matrix ret = lhs;
+	ret -= rhs;
+	return ret;
+}
+Matrix operator*(const Matrix& lhs, const Matrix& rhs) {
+	Matrix ret = lhs;
+	ret *= rhs;
+	return ret;
+}
+
+std::ostream& operator<<(std::ostream& lhs, const Matrix& rhs) {
+	return lhs << rhs.values[0] << "," << rhs.values[1] << std::endl << rhs.values[2] << "," << rhs.values[3] << std::endl;
+}
+std::istream& operator>>(std::istream& lhs, Matrix& rhs) {
+	return lhs >> rhs.values[0] >> rhs.values[1] >> rhs.values[2] >> rhs.values[3];
+}
diff --git a/week07/Exercise6.h b/week07/Exercise6.h
new file mode 100644
index 0000000..ab5df9e
--- /dev/null
+++ b/week07/Exercise6.h
@@ -0,0 +1,27 @@
+#include <iostream>
+
+class Matrix {
+	int values[4];
+
+	void addBy(int amount);
+
+public:
+	Matrix(int a, int b, int c, int d);
+
+	Matrix& operator++();
+	Matrix operator++(int);
+	Matrix& operator--();
+	Matrix operator--(int);
+
+	Matrix& operator+=(const Matrix& rhs);
+	Matrix& operator-=(const Matrix& rhs);
+	Matrix& operator*=(const Matrix& rhs);
+
+	friend Matrix operator+(const Matrix& lhs, const Matrix& rhs);
+	friend Matrix operator-(const Matrix& lhs, const Matrix& rhs);
+	friend Matrix operator*(const Matrix& lhs, const Matrix& rhs);
+
+	friend std::ostream& operator<<(std::ostream& lhs, const Matrix& rhs);
+	friend std::istream& operator>>(std::istream& lhs, Matrix& rhs);
+};
+
diff --git a/week07/README.md b/week07/README.md
new file mode 100644
index 0000000..ea64212
--- /dev/null
+++ b/week07/README.md
@@ -0,0 +1,71 @@
+# Задачи - ООП, Седмица 7, 04.04.2024
+
+*Този файл е копие на задачите от: [syndamia.com/teaching/oop-2023/week7](https://syndamia.com/teaching/oop-2023/week7)*
+
+## Преговорни
+
+### Задача 1 - Голяма петица
+
+Една съставка е композирана от низ (с максимална дължина от 511 знака) определящ името ѝ и грамаж (число с плаваща запетая).
+
+Създайте клас `Recipe`, към който могат да се прибавят и премахват произволен брой съставки.
+Имплементирайте голяма петица (голяма четворка плюс move семантики) за него.
+
+### Задача 2 - Работа с файлове
+
+От един ред на входа получавате името на текстови файл.
+Изкарайте на екрана средната една трета от файла, като буквите са в обратен ред.
+
+## Лесни задачи
+
+### Задача 3
+
+Имплементирайте клас `Thermometer`, който запазва максималната и минималната възможна температура за измерване, както и сегашната температура, всичките които са цели неотрицателни числа.
+
+Имплементирайте методи `SaveText` и `LoadText`, които съответно записват и четат (тоест член-данните стават равни на тези от файла) данните си в/от **текстови** файл с подадено име.
+Аналогично имплементирайте `SaveBinary` и `LoadBinary`, които работят с **двоични** файлове.
+
+### Задача 4
+
+Имплементирайте клас `Street`, който запазва скрито името на улицата като низ с произволна дължина и номер като цяло число.
+Имплементирайте голяма петица.
+
+Имплементирайте методите `SaveText`, `LoadText`, `SaveBinary`, `LoadBinary`.
+
+### Задача 5
+
+За един транспортен билет е нужно скрито да пазим началната и крайната дестинация като динамично-заделени низове с произволна дължина, неговата цена като число с плаваща запетая и идентификационен номер като цяло неотрицателно число.
+
+Имплементирайте голяма петица и четирите функции за запазване и четене от файлове на съответния клас.
+
+### Задача 6
+
+Имплементирайте клас `Matrix`, който запазва стойностите на матрица 2 на 2.
+Предефинирайте операторите за инкрементиране, декрементиране, събиране, изваждане, умножение и вход/изход от/към поток.
+
+Имплементирайте четирите функции за записване и четене от файлове.
+
+### Задача 7
+
+Имплементирайте клас `Paragraph`, който съдържа текст с много редове в него.
+Текстът се запазва като низ с произволна дължина, а редовете се разделят със знака `'\n'`.
+
+Имплементирайте голяма петица.
+Имплементирайте четирите функции за записване и четене от файлове.
+
+Имплементирайте операторите за събиране, които копират текстът от подадения параграф и го вмъкват в края на сегашния; оператор[] който връща начален указател на i-тия ред; операторите за (лексикографско) сравнение; вход/изход от/към поток.
+
+## Трудни задачи
+
+### Задача 8
+
+Имплементирайте клас `MatrixNМ`, който запазва стойностите на матрица с N реда и M колони (подадени на конструктор).
+
+Имплементирайте голяма петица.
+Имплементирайте четирите функции за записване и четене от файлове.
+
+Имплементирайте операторите за събиране, изваждане, умножение и деление (нека да дефинираме деление на две матрици като умножението на първата матрица по транспонираната втората матрица върху детерминантата ѝ).
+Ако някоя операция не е възможна, върнете съответна стойност по подразбиране.
+
+Имплементирайте оператор[], като индекса i е числена конкатенация на двете координати, разделени с нула (тоест ако искаме стойността на ред 27 и колона 9, тогава ще въведем индекса 2709).
+Имплементирайте оператори за равенство, инкрементиране, декрементиране, побитово отместване (прилага се върху всяка стойност в матрицата), логически (&& връща true само ако двете матрици са равни, || връща true ако имат еднакви размерности и съществува поне един равен елемент на еднакви индекси).