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Essential C++--Exercise of Chpt.4

Resin_Wu 2022-02-11 阅读 30
c++visual studioc语言

Essential C++--Exercise of Chpt.4

前言

  本文用于记录阅读书籍《Essential C++》Chpt.4后完成课后习题。

正文（Code）

4.1 First Meeting with Header File

  建立stack.h和stack.suffix，此处的suffix是你的编译器所能接受的扩展名，或是你的项目所使用的扩展名。编写main()函数，练习操作Stack的所有公开接口，并加以编译执行。程序代码文件和main()都必须包含stack.h。

#include <iostream>
#include <string>

#include "stack.h"

using namespace std;

bool get_another_try()
{
	char c_in;
	bool bTry;
	
	cout << "try it? (Y/y:yes N/n:no): ";
	cin >> c_in;

	bTry = ('Y' == c_in || 'y' == c_in);

	if (!bTry && 'N' != c_in && 'n' != c_in)
	{
		cout << "invalid input: " << c_in << endl;
	}

	return bTry;
}

int main()
{
	Stack stk;
	int r;

	r = init_stack(stk);
	if (0 != r)
	{
		cout << "init stack failed!" << endl;
		return -1;
	}

	string str_tmp;
	while(get_another_try())
	{
		cout << "pls input test choice(0:test pop, 1:test peek, 2:test empty, 3:test full): ";
		cin >> r;

		switch(r)
		{
			// test pop
			case 0:
			{
				if (!(stk.pop(str_tmp)))
				{
					cout << "test pop failed!" << endl;
					break;
				}
				cout << "get pop string: " << str_tmp 
					 << ", cur size: " << stk.size() << endl;
				break;
			}

			// test peek
			case 1:
			{
				if (!(stk.peek(str_tmp)))
				{
					cout << "test peek failed!" << endl;
					break;
				}
				cout << "get peek string: " << str_tmp
					 << ", cur size: " << stk.size() << endl;
				break;
			}

			// test empty
			case 2:
			{
				bool bEmpty = stk.empty();
				cout << "get empty: " << bEmpty
					 << ", cur size: " << stk.size() << endl;
				break;
			}

			// test full
			case 3:
			{
				bool bFull = stk.full();
				cout << "get full: " << bFull
					 << ", cur size: " << stk.size() << endl;
				break;
			}
			default:
			{
				cout << "invalid input: " << r
					 << ", cur size: " << stk.size() << endl;
				break;
			}
		}
	}

	cout << "user exit!" << endl;
	return 0;
}

  stack.cpp源文件如下所述：

#include "stack.h"

using namespace std;

bool
Stack::find(const string &str)
{
	vector<string>::iterator it = _stack.begin();

	while(it != _stack.end())
	{
		if (*it == str)
		{
			break;
		}

		it++;
	}

	return it != _stack.end();
}

int
Stack::count(const string &str)
{
	int cnt = 0;
	
	vector<string>::iterator it = _stack.begin();

	while(it != _stack.end())
	{
		if (*it == str)
		{
			cnt++;
		}

		it++;
	}

	return cnt;
}

int init_stack(Stack &stk)
{
	string str_arr[6] = {"a", "ab", "abc", "abcd", "abcde", "abcdef"};

	for(int i = 0; i < 6; i++)
	{
		stk.push(str_arr[i]);
	}
	
	return 0;
}

  stack.h头文件如下所述：

#ifndef _STACK_H_
#define _STACK_H_

#include <iostream>
#include <string>
#include <vector>

using namespace std;

class Stack
{
public:
	bool empty();
	bool full();
	bool peek(string &);
	bool pop(string &);
	bool push(const string &);

	bool find(const string &);
	int count(const string &);
	
	int size();

private:
	vector<string> _stack;
};

inline bool
Stack::empty(void)
{
	return _stack.empty();
}

inline bool
Stack::full(void)
{
	return (_stack.size() == _stack.max_size());
}

inline bool
Stack::peek(string &str)
{
	if (_stack.empty())
	{
		return false;
	}

	str = _stack.back();
	return true;
}

inline bool
Stack::pop(string &str)
{
	if (_stack.empty())
	{
		return false;
	}

	str = _stack.back();
	_stack.pop_back();
	return true;
}

inline bool
Stack::push(const string &str)
{
	_stack.push_back(str);
	return true;
}

inline int
Stack::size()
{
	return _stack.size();
}

int init_stack(Stack &stk);

#endif

4.2 Expand Class Stack

  扩展Stack的功能，以支持find()和count()两个操作。find()会查看某值是否存在而返回true或false。count()返回某字符串的出现次数。重新实现练习4.1的main()，让它调用这两个函数。

#include <iostream>
#include <string>

#include "stack.h"

using namespace std;

bool get_another_try()
{
	char c_in;
	bool bTry;
	
	cout << "try it? (Y/y:yes N/n:no): ";
	cin >> c_in;

	bTry = ('Y' == c_in || 'y' == c_in);

	if (!bTry && 'N' != c_in && 'n' != c_in)
	{
		cout << "invalid input: " << c_in << endl;
	}

	return bTry;
}

int main()
{
	Stack stk;
	int r;

	r = init_stack(stk);
	if (0 != r)
	{
		cout << "init stack failed!" << endl;
		return -1;
	}

	string str_tmp;
	while(get_another_try())
	{
		cout << "pls input test choice(0:test pop, 1:test peek, 2:test empty, 3:test full, 4:test find, 5:test count): ";
		cin >> r;

		switch(r)
		{
			// test pop
			case 0:
			{
				if (!(stk.pop(str_tmp)))
				{
					cout << "test pop failed!" << endl;
					break;
				}
				cout << "get pop string: " << str_tmp 
					 << ", cur size: " << stk.size() << endl;
				break;
			}

			// test peek
			case 1:
			{
				if (!(stk.peek(str_tmp)))
				{
					cout << "test peek failed!" << endl;
					break;
				}
				cout << "get peek string: " << str_tmp
					 << ", cur size: " << stk.size() << endl;
				break;
			}

			// test empty
			case 2:
			{
				bool bEmpty = stk.empty();
				cout << "get empty: " << bEmpty
					 << ", cur size: " << stk.size() << endl;
				break;
			}

			// test full
			case 3:
			{
				bool bFull = stk.full();
				cout << "get full: " << bFull
					 << ", cur size: " << stk.size() << endl;
				break;
			}

			// test find
			case 4:
			{
				cout << "pls input string you wanna find: ";
				cin >> str_tmp;
				
				if (stk.find(str_tmp))
				{
					cout << "find string: " << str_tmp << ", from class stack" << endl;
				}
				else
				{
					cout << "not find string: " << str_tmp << endl;
				}
				break;
			}

			// test count
			case 5:
			{
				cout << "pls input string you wanna find: ";
				cin >> str_tmp;

				r = stk.count(str_tmp);

				cout << "find string: " << str_tmp << ", count: " << r << endl;
				break;
			}
			default:
			{
				cout << "invalid input: " << r
					 << ", cur size: " << stk.size() << endl;
				break;
			}
		}
	}

	cout << "user exit!" << endl;
	return 0;
}

  注：拓展后的stack.cpp和stack.h参考4.1小节。

4.3 Create A new Class Including Several Data

  考虑一下所定义的全局(global)数据：

	string program_name;
	string version_stamp;
	int version_number;
	int tests_run;
	int tests_passed;

  类代码如下所示：

#include <iostream>
#include <string>

using namespace std;

class UserProfile
{
public:
	string program_name;
	string version_stamp;
	int version_number;
	int tests_run;
	int tests_passed;
};

4.4 Create A new Class UserProfile

  一份“用户概况记录(user profile)”内含以下数据：登录记录、实际姓名、登入次数、猜过次数、猜对次数、等级—包括初级、中级、高级、专家，以及猜对百分比（可实时计算获得，或将其值存起来备用）。请写出一个名为UserProfile的class，提供以下操作：输入、输出、相等测试、不等测试。其constructor必须能够处理默认的用户等级、默认的登录名称("guest")。对于同样名为guest的多个用户，你如何保证每个guest有他自己独有的登录会话(login session)，不会和其他人混淆？

#include <iostream>
#include <string>

#include "user_profile.h"

int main()
{
#if 1  // create an object, using default constructor
	cout << "===== demo_1: create a class object, by default constructor! ====" << endl;

	UserProfile user_profile;
	string level2str[] = {"low", "middle", "high", "expert"};

	cout << "user_name: " << user_profile.get_usr_name() << endl;
	cout << "user_level: " << level2str[user_profile.get_usr_level()] << endl;

	cout << "create object user_profile by default constructor end!" << endl;
	cout << endl;
#endif

#if 1  // input an object by istream
	cout << "===== demo_2: create a class object by istream! ====" << endl;

	UserProfile user_profile_1;

	cin >> user_profile_1;    // std in
	//user_profile_1.pr_obj();  // print object info

	cout << "create user_profile_1 end!" << endl;
	cout << endl;
#endif

#if 1  // output an object by ostream
	cout << "===== demo_3: output a class object by ostream! ====" << endl;

	cout << user_profile_1 << endl;

	cout << "output user_profile_1 end!" << endl;
	cout << endl;
#endif

#if 1  // equality function of class
	cout << "===== demo_4: equality test! ====" << endl;

	UserProfile user_profile_2;

	cin >> user_profile_2;	  // std in
	user_profile_2.pr_obj();  // print object info

	cout << "get equality result: " << (user_profile_2 == user_profile_1) << endl;
	cout << "equality test end!" << endl;
	cout << endl;
#endif

#if 1  // inequality function of class
	cout << "===== demo_5: inequality test! ====" << endl;

	UserProfile user_profile_3;

	cin >> user_profile_3;	  // std in
	user_profile_3.pr_obj();  // print object info

	cout << "get inequality result: " << (user_profile_3 == user_profile_2) << endl;
	cout << "inequality test end!" << endl;
	cout << endl;
#endif

	cout << "demo end!" << endl;
	return 0;
}

  包含类UserProfile的头文件如下所述：

#ifndef _USER_PROFILE_H_
#define _USER_PROFILE_H_

#include <iostream>
#include <string>
#include <ctime>

using namespace std;

enum UserLevel_E
{
	low_level,
	middle_level,
	high_level,
	expert_level,
};

class UserProfile
{
public:
	UserProfile();  // default constructor
	
	friend ostream& operator<< (ostream &os, UserProfile &user_profile);
	friend istream& operator>> (istream &is, const UserProfile &user_profile);
	bool operator== (const UserProfile &user_profile);
	bool operator!= (const UserProfile &user_profile);

	// login_date
	string get_usr_login_date() {return _login_date;}
	int set_usr_login_date();

	// user_name
	string get_usr_name() {return _user_name;}
	int set_usr_name(const string &usr_name);

	// login_cnt
	int get_login_cnt() {return _login_cnt;}
	int set_login_cnt(const int &login_cnt);

	// user_guess_cnt
	int get_usr_guess_cnt() {return _user_guess_cnt;}
	int set_usr_guess_cnt(const int &usr_guess_cnt);

	// user_guess_correct_cnt
	int get_usr_guess_correct_cnt() {return _user_guess_correct_cnt;}
	int set_usr_guess_correct_cnt(const int &usr_guess_cor_cnt);

	// user_level
	UserLevel_E get_usr_level() {return _user_level;}
	int set_usr_level(const UserLevel_E &usr_level);

	// user_guess_percentage
	float get_usr_guess_percentage() {return _user_guess_percentage;}
	int set_usr_guess_percentage();

	void pr_obj() const;

private:
	string _login_date;
	string _user_name;
	int _login_cnt;
	int _user_guess_cnt;
	int _user_guess_correct_cnt;
	UserLevel_E _user_level;
	float _user_guess_percentage;
};

// constructor, default
inline UserProfile::UserProfile()
{
	_user_level = middle_level;
	_user_name = "guest";
}

inline bool
UserProfile::operator== (const UserProfile &user_profile)
{
	return (("guest" != this->_user_name) && (this->_user_name == user_profile._user_name));
}

inline bool
UserProfile::operator!= (const UserProfile &user_profile)
{
	return (this->_user_name != user_profile._user_name);
}

inline int 
UserProfile::set_usr_login_date()
{
	char str_buf[64];  // used for storing date-string
	
	// todo: get current date
	time_t tm;
	time(&tm);

	struct tm stTm;
	localtime_r(&tm, &stTm);
	
	// todo: convert into string
	strftime(str_buf, 64, "%Y-%m-%d %H-%M-%S", &stTm);

	this->_login_date = str_buf;
	return 0;
}

inline int 
UserProfile::set_usr_name(const string &usr_name)
{
	this->_user_name = usr_name;
	return 0;
}

inline int 
UserProfile::set_login_cnt(const int &login_cnt)
{
	this->_login_cnt = login_cnt;
	return 0;
}

inline int 
UserProfile::set_usr_guess_cnt(const int &usr_guess_cnt)
{
	this->_user_guess_cnt = usr_guess_cnt;
	return 0;
}

inline int 
UserProfile::set_usr_guess_correct_cnt(const int &usr_guess_cor_cnt)
{
	this->_user_guess_correct_cnt = usr_guess_cor_cnt;
	return 0;
}

inline int
UserProfile::set_usr_level(const UserLevel_E &usr_level)
{
	this->_user_level = usr_level;
	return 0;
}

inline int 
UserProfile::set_usr_guess_percentage()
{
	this->_user_guess_percentage = (this->_user_guess_cnt == 0 ? 0.0f : ((float)this->_user_guess_correct_cnt / (float)this->_user_guess_cnt));
	return 0;
}

inline void
UserProfile::pr_obj() const
{
	cout << *(UserProfile *)this << endl;
}

ostream& operator<< (ostream &os, UserProfile &user_profile)
{
	string level2str[] = {"low", "middle", "high", "expert"};

	os << "user_name: " << user_profile.get_usr_name() << '\n';
	os << "login_date: " << user_profile.get_usr_login_date() << '\n';
	os << "login_cnt: " << user_profile.get_login_cnt() << '\n';
	os << "user_guess_cnt: " << user_profile.get_usr_guess_cnt() << '\n';
	os << "user_guess_correct_cnt: " << user_profile.get_usr_guess_correct_cnt() << '\n';
	os << "user_level: " << level2str[user_profile.get_usr_level()] << '\n';
	os << "user_guess_percentage: " << user_profile.get_usr_guess_percentage();
	
	return os;
}

istream& operator>> (istream &is, UserProfile &user_profile)
{
	// input format: user_name, login_date, login_cnt, user_guess_cnt, user_guess_correct_cnt, user_level
	
	string usr_name;
	int login_cnt, usr_level;
	float usr_guess_cnt, usr_guess_cor_cnt;

	cout << "user_name: ";
	is >> usr_name;

	cout << "login_cnt: ";
	is >> login_cnt;

	cout << "user_guess_cnt: ";
	is >> usr_guess_cnt;

	cout << "user_guess_correct_cnt: ";
	is >> usr_guess_cor_cnt;

	cout << "user_level(0:low, 1:middle, 2:high, 3:expert): ";
	is >> usr_level;

	// update input into class object
	user_profile.set_usr_login_date();
	user_profile.set_usr_name(usr_name);
	user_profile.set_login_cnt(login_cnt);
	user_profile.set_usr_guess_cnt(usr_guess_cnt);
	user_profile.set_usr_guess_correct_cnt(usr_guess_cor_cnt);
	user_profile.set_usr_level((UserLevel_E)usr_level);
	user_profile.set_usr_guess_percentage();

	return is;
}
#endif

4.5 Create A new Class Matrix

  请实现一个4x4的Matrix class，至少提供以下接口：矩阵加法、矩阵乘法、打印函数print()、复合运算符+=，以及一组支持下标操作(subscripting)的function call运算符，像下面这样：

	float& operator() (int row, int column);
	float operator() (int row, int column) const;

  主进程调试源代码如下所述：

#include <iostream>
#include <string>

#include "matrix.h"

using namespace std;

int main()
{
#if 1  // create matrix obj 0, by default constructor
	cout << "=== create matrix obj 0, by default constructor ===" << endl;
	
	Matrix matrix_0;

	// dbg: print matrix info
	matrix_0.pr_matrix();
	
	cout << endl;
#endif

#if 1  // create matrix obj 1, using array which size if 16
	cout << "=== create matrix obj 1, using array which size if 16 ===" << endl;

	float arr[16] = {0,1,2,3,  4,5,6,7,  8,9,10,11,  12,13,14,15};
	Matrix matrix_1(arr);

	// dbg: print matrix info
	matrix_1.pr_matrix();

	cout << endl;
#endif

#if 1  // matrix add
	cout << "=== test matrix add ===" << endl;

	matrix_0.matrix_add(matrix_1);
	
	// dbg: print matrix info
	matrix_0.pr_matrix();

	cout << "test matrix add end!" << endl;
	cout << endl;
#endif

#if 1  // matrix multiple
	cout << "=== test matrix multiple ===" << endl;

	matrix_0.matrix_multi(matrix_1);

	// dbg: print matrix info
	matrix_0.pr_matrix();

	cout << "test matrix multiple end!" << endl;
	cout << endl;
#endif

#if 1
	cout << "=== test operator += ===" << endl;

	matrix_0 += matrix_1;

	// dbg: print matrix info
	matrix_0.pr_matrix();

	cout << "test operator += end!" << endl;
	cout << endl;
#endif

#if 1
	cout << "=== test subscripting ===" << endl;

	int row, col;
	cout << "input row(0~3): ";
	cin >> row;
	cout << "input column(0~3): ";
	cin >> col;
	
	// dbg: print matrix info
	float r = matrix_0(row, col);

	cout << "test subscripting end! get r: " << r << endl;
	cout << endl;
#endif

	cout << "demo end!" << endl;
	return 0;
}

  包含类Matrix定义的头文件如下所述：

#ifndef _MATRIX_H_
#define _MATRIX_H_

#include <iostream>
#include <string>

using namespace std;

class Matrix
{
public:
	Matrix();
	Matrix(float arr[16]);

	bool check_attr() const;      // check if attribute of object is valid, true:valid, false:invalid
	
	int matrix_add(Matrix &a);
	int matrix_multi(Matrix &a);
	void pr_matrix();
	int operator+=(Matrix &a);

	float& operator() (int row, int column);
	float operator() (int row, int column) const;
	
private:
	int _row;   // row of matrix, fixed
	int _col;   // column of matrix, fixed

	// todo: try using 2-d vector
	float _matrix_arr[4][4];  // vector<vector<float>> _matrix;
};

inline 
Matrix::Matrix()
{
	// initialize matrix size
	this->_row = 4;
	this->_col = 4;
	
	cout << "pls input default matrix(float): " << endl;

	for(int i = 0; i < this->_row; i++)
	{
		for(int j = 0; j < this->_col; j++)
		{
			cout << "(" << i << ", " << j << "): ";
			cin >> this->_matrix_arr[i][j];
		}
	}
}

inline 
Matrix::Matrix(float arr[16])
{
	// initialize matrix size
	this->_row = 4;
	this->_col = 4;

	for(int i = 0; i < this->_row; i++)
	{
		for(int j = 0; j < this->_col; j++)
		{
			this->_matrix_arr[i][j] = arr[i*this->_col + j];
		}
	}
}

inline bool
Matrix::check_attr() const
{
	return (this->_row == 4 && this->_col == 4);
}

inline int
Matrix::matrix_add(Matrix & a)
{
	if (!this->check_attr())
	{
		return -1;
	}
	
	for(int i = 0; i < this->_row; i++)
	{
		for(int j = 0; j < this->_col; j++)
		{
			this->_matrix_arr[i][j] += a._matrix_arr[i][j];
		}
	}
	
	return 0;
}

inline int
Matrix::matrix_multi(Matrix & a)
{
	if (!this->check_attr())
	{
		return -1;
	}
	
	for(int i = 0; i < this->_row; i++)
	{
		for(int j = 0; j < this->_col; j++)
		{
			this->_matrix_arr[i][j] *= a._matrix_arr[i][j];
		}
	}

	return 0;
}

inline void
Matrix::pr_matrix()
{
	if (!this->check_attr())
	{
		return;
	}

	for(int i = 0; i < this->_row; i++)
	{
		for(int j = 0; j < this->_col; j++)
		{
			cout << this->_matrix_arr[i][j] << " ";
		}
		cout << endl;
	}
}

inline int
Matrix::operator+= (Matrix &a)
{
	this->matrix_add(a);   // reuse function matrix_add
	return 0;
}

inline float& 
Matrix::operator() (int row, int column)
{
	if (!this->check_attr())
	{
		cout << "invalid obj attr! row: " << this->_row << ", col: " << this->_col << endl;
		return this->_matrix_arr[0][0];
	}

	if (row < 0 || row >= this->_row
		|| column < 0 || column >= this->_col)
	{
		cout << "invalid args! row: " << row << ", col: " << column << endl;
		return this->_matrix_arr[0][0];
	}
	
	return this->_matrix_arr[row][column];
}

inline float
Matrix::operator() (int row, int column) const
{
	if (!Matrix::check_attr())
	{
		cout << "invalid obj attr! row: " << this->_row << ", col: " << this->_col << endl;
		return this->_matrix_arr[0][0];
	}

	if (row < 0 || row >= this->_row
		|| column < 0 || column >= this->_col)
	{
		cout << "invalid args! row: " << row << ", col: " << column << endl;
		return this->_matrix_arr[0][0];
	}

	return this->_matrix_arr[row][column];
}
#endif

结语

  个人阅读书籍《Essential C++》之余创建此专栏，用于记录完成每一章节后附录的exercise。如有问题，请各位不吝指正。

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