C++ Primer 07 Exercise

01

#include <iostream>
double cal(double x, double y);

int main()
{
	using namespace std;
	double x, y;
	
	do
	{
		cout << "두 수를 입력하세요 (0 입력시 종료) : \n";
		cout << "첫번째 수 : ";
		cin >> x;
		if (x == 0)
			break ;
		cout << "두번째 수 : ";
		cin >> y;
		if (y == 0)
			break;
		cout << "두 수의 조화평균은 " << cal(x, y) << "입니다.\n";
	}
	while (x != 0 && y != 0);
	cout << "프로그램을 종료합니다.\n";
	return 0;
}

double cal(double x, double y)
{
	return 2.0 * x * y / (x + y);
}

02

#include <iostream>
using namespace std;
int input(int* score);
void output(int* score, int count);
void average(int* score, int count);

int main()
{
	int score[10];
	int count = input(score);
	output(score, count);
	average(score, count);
	return 0;
}

int input(int* score)
{
	int i;
	for (i = 0; i < 10; i++)
	{
		cout << i << "번째 스코어를 입력하세요 (음수 입력시 입력 종료) : ";
		cin >> score[i];
		if (score[i] < 0)
			break;
	}
	return i;
}

void output(int* score, int count)
{
	cout << "획득 스코어 : ";
	for (int i = 0; i < count; i++)
		cout << score[i] << " ";
	cout << endl;
}

void average(int* score, int count)
{
	double sum = 0;
	for (int i = 0; i < count; i++)
		sum += score[i];
	cout << "평균 스코어는 " << sum / count << "점 입니다.\n"; 
}

03

a)

void ouput(box a)
{
	cout << "메이커 : " << a.maker << endl;
	cout << "높이 : " << a.height << endl;
	cout << "넓이 : " << a.width << endl;
	cout << "길이 : " << a.length << endl;
	cout << "부피 : " << a.volume << endl;
}

b)

void set_volume(box *a)
{
	a->volume = a->height * a->length * a->width;
}

c)

#include <iostream>
using namespace std;
struct box
{
	char maker[40];
	float height;
	float width;
	float length;
	float volume;
};

void output(box a);
void set_volume(box *a);

int main()
{
	box a;
	cout << "박스 정보를 입력하세요\n";
	cout << "박스 메이커 : ";
	cin >> a.maker;
	cout << "박스 높이 : ";
	cin >> a.height;
	cout << "박스 가로길이 : ";
	cin >> a.width;
	cout << "박스 세로길이 : ";
	cin >> a.length;
	set_volume(&a);
	output(a);
	return 0;
}

void output(box a)
{
	cout << "\n박스의 정보는 다음과 같습니다.\n";
	cout << "메이커 : " << a.maker << endl;
	cout << "높이 : " << a.height << endl;
	cout << "가로 : " << a.width << endl;
	cout << "세로 : " << a.length << endl;
	cout << "부피 : " << a.volume << endl;
}

void set_volume(box *a)
{
	a->volume = a->height * a->length * a->width;
}

04

#include <iostream>
long double probability(unsigned numbers, unsigned picks, unsigned p_min, unsigned p_max);

int main()
{
	using namespace std;
	double total, choices;
	double p_max, p_min;
	cout << "전체 수의 개수와 뽑을 수의 개수를 입력하십시오 : \n";
	while ((cin >> total >> choices) && choices <= total)
	{
		cout << "파워볼을 뽑을 범위의 최소값을 입력하십시오 : ";
		cin >> p_min;
		cout << "파워볼을 뽑을 범위의 최대값을 입력하십시오 : ";
		cin >> p_max;

		cout << "당신이 이길 확률은 ";
		cout << probability(total, choices, p_min, p_max);
		cout << "번 중에서 한번입니다.\n";
		cout <<"다시 두 수를 입력하십시오. (끝내려면 q를 입력) : ";
	}
	cout << "프로그램을 종료합니다.\n";
	return 0;
}

long double probability(unsigned numbers, unsigned picks, unsigned p_min, unsigned p_max)
{
	long double result = 1.0;
	long double n;
	unsigned p;

	for (n = numbers, p = picks; p > 0; n--, p--)
		result = result * n / p;
	result = result / (p_max - p_min + 1);
	return result;
}

05

#include <iostream>
long double factorial(long double x);

int main()
{
	using namespace std;

	cout << "수를 입력하세요 (음수 입력시 종료) : ";
	long double num;
	while (cin >> num && num > 0)
	{
		cout << num << "! = " << factorial(num) << endl;
		cout << "수를 입력하세요 (음수 입력시 종료) : ";
	}
	cout << "프로그램을 종료합니다.\n";
	return 0;
}

long double factorial(long double x)
{
	if (x == 0)
		return 1;
	return x * (factorial(x - 1));
}

06

#include <iostream>
using namespace std;
const int SIZE = 5;

int Fill_array(double* arr, int size);
void Show_array(double* arr, int size);
void Reverse_array(double *arr, int size);

int main()
{
	double arr[SIZE];
	int real_size;
	real_size = Fill_array(arr, SIZE);
	Show_array(arr, real_size);
	
	Reverse_array(arr, real_size);
	Show_array(arr, real_size);
	
	Reverse_array(arr, real_size);
	double temp;
	temp = arr[0];
	arr[0] = arr[real_size - 1];
	arr[real_size - 1] = temp;
	Show_array(arr, real_size);

	return 0;
}

int Fill_array(double* arr, int size)
{
	cout << "배열에 저장할 값들을 입력하세요\n";
	
	int i;
	for (i = 0; i < size; i++)
	{
		cout << i + 1 << "번째 값 : ";
		if (!(cin >> arr[i]))
			break;	
	}
	return i;
}

void Show_array(double* arr, int size)
{
	cout << "배열의 값들을 출력합니다.\n";
	for (int i = 0; i < size; i++)
		cout << i + 1 << "번째 값 : " << arr[i] << endl;
}

void Reverse_array(double *arr, int size)
{
	cout << "배열의 값들을 재정렬합니다.\n";
	double temp;
	for (int i = 0; i < size / 2; i++)
	{
		temp = arr[i];
		arr[i] = arr[size - i - 1];
		arr[size - i - 1] = temp;
	}
}

07

// arfupt.cpp

#include <iostream>
const int Max = 5;
double* fill_array(double *start, double *end);
void show_array(double* start, double* end);
void revalue(double r, double* start, double* end);

int main()
{
	using namespace std;
	double properties[Max];

	double* pt = fill_array(properties, properties + Max);
	show_array(properties, pt);
	if (pt != properties)
	{
		cout << "재평가율을 입력하십시오 : ";
		double factor;
		while (!(cin >> factor))
		{
			cin.clear();
			while (cin.get() != '\n')
				continue;
			cout << "잘못 입력했습니다, 수치를 입력하세요 : ";
		}
		revalue(factor, properties, pt);
		show_array(properties, pt);
	}
	cout << "프로그램을 종료합니다.\n";
	return 0;
}

double* fill_array(double *start, double *end)
{
	using namespace std;
	double temp;
	double *pt;
	int i = 0;
	for (pt = start; pt != end; pt++)
	{
		cout << (i + 1) << "번 부동산의 가격 : $";
		cin >> temp;
		if (!cin)
		{
			cin.clear();
			while (cin.get() != '\n')
				continue;
				cout << "입력 불량; 입력 과정을 끝내겠습니다.\n";
				break;
		}
		else if (temp < 0)
			break;
		*pt = temp;
		i++;
	}
	return pt;
}

void show_array(double* start, double* end)
{
	using namespace std;
	double *pt;
	int i = 0;
	for (pt = start; pt != end; pt++)
	{
		cout << (i + 1) << "번 부동산 : $";
		cout << *pt << endl;
	}
}

void revalue(double r, double* start, double* end)
{
	double *pt;
	for (pt = start; pt != end; pt++)
		*pt *= r;
}

08

a)

#include <iostream>
#include <array>
#include <string>
const int Seasons = 4;
const char * Sname[Seasons] = {"Spring", "Summer", "Fail", "Winter"};

void fill(std::array<double, Seasons> *pa);
void show(std::array<double, Seasons> da);

int main()
{
	std::array<double, Seasons> expenses;
	fill(&expenses);
	show(expenses);
	return 0;
}

void fill(std::array<double, Seasons> * pa)
{
	using namespace std;
	for (int i = 0; i < Seasons; i++)
	{
		cout << Sname[i] << "에 소요되는 비용 : ";
		cin >> (*pa)[i];
	}
}

void show(std::array<double, Seasons> da)
{
	using namespace std;
	double total = 0.0;
	cout << "\n계졀별 비용\n";
	for (int i = 0; i < Seasons; i++)
	{
		cout << Sname[i] << " : $" << da[i] << endl;
		total += da[i];
	}
	cout << "총 비용 : $" << total << endl;
}

b)

#include <iostream>
#include <array>
#include <string>
const int Seasons = 4;
const char * Sname[Seasons] = {"Spring", "Summer", "Fail", "Winter"};
struct money
{
	double expense[Seasons];
};

void fill(money *pa);
void show(money pa);

int main()
{
	money pa;
	fill(&pa);
	show(pa);
	return 0;
}

void fill(money *pa)
{
	using namespace std;
	for (int i = 0; i < Seasons; i++)
	{
		cout << Sname[i] << "에 소요되는 비용 : ";
		cin >> pa->expense[i];
	}
}

void show(money pa)
{
	using namespace std;
	double total = 0.0;
	cout << "\n계졀별 비용\n";
	for (int i = 0; i < Seasons; i++)
	{
		cout << Sname[i] << " : $" << pa.expense[i] << endl;
		total += pa.expense[i];
	}
	cout << "총 비용 : $" << total << endl;
}

09

#include <iostream>
using namespace std;

const int SLEN = 30;
struct student
{
	char fullname[SLEN];
	char hobby[SLEN];
	int ooplevel;
};

int getinfo(student pa[], int n);
void display1(student st);
void display2(const student* ps);
void display3(const student pa[], int n);

int main()
{
	cout << "학급의 학생 수를 입력하십시오 : ";
	int class_size;
	cin >> class_size;
	while (cin.get() != '\n')
		continue;
	
	student * ptr_stu = new student[class_size];
	int entered = getinfo(ptr_stu, class_size);
	for (int i = 0; i < entered; i++)
	{
		display1(ptr_stu[i]);
		display2(&ptr_stu[i]);
	}
	display3(ptr_stu, entered);
	cout << "프로그램을 종료합니다.\n";
	return 0;
}

int getinfo(student pa[], int n)
{
	int i;
	for (i = 0; i < n; i++)
	{
		cout << i + 1 << "번째 학생의 정보를 입력합니다.\n";
		cout << "이름을 입력하세요 : ";
		if (!cin.get(pa[i].fullname, SLEN))
			break;
		cout << "취미를 입력하세요 : ";
		cin >> pa[i].hobby;
		cout << "레벨을 입력하세요 : ";
		cin >> pa[i].ooplevel;
		cin.get();
	}
	cout << "입력을 종료합니다.\n";
	return i;
}

void display1(student st)
{
	cout << "학생의 이름 : " << st.fullname << endl;
	cout << "학생의 취미 : " << st.hobby << endl;
	cout << "학생의 레벨 : " << st.ooplevel << endl;
}

void display2(const student* ps)
{
	cout << "학생의 이름 : " << ps->fullname << endl;
	cout << "학생의 취미 : " << ps->hobby << endl;
	cout << "학생의 레벨 : " << ps->ooplevel << endl;
}

void display3(const student pa[], int n)
{
	for (int i = 0; i < n; i++)
	{
		cout << i + 1 << "번째 학생의 정보를 출력합니다.\n";
		cout << "학생의 이름 : " << pa[i].fullname << endl;
		cout << "학생의 취미 : " << pa[i].hobby << endl;
		cout << "학생의 레벨 : " << pa[i].ooplevel << endl;
	}
}

10

#include <iostream>
using namespace std;

double calculate(double x, double y, double (*pt)(double, double));
double add(double x, double y);
double sub(double x, double y);
double mul(double x, double y);
double div(double x, double y);

int main()
{
	double (*pf[4])(double, double) = {add, sub, mul, div};
	double x, y;
	cout << "두 수를 입력하세요 : \n";
	while (cin >> x >> y)
	{
		cout << "add : " << calculate(x, y, pf[0]) << endl;
		cout << "sub : " << calculate(x, y, pf[1]) << endl;
		cout << "mul : " << calculate(x, y, pf[2]) << endl;
		cout << "div : " << calculate(x, y, pf[3]) << endl;
		cout << "두 수를 입력하세요 : \n";
	}
	
	return 0;
}

double calculate(double x, double y, double (*pt)(double, double))
{
	return pt(x, y);
}

double add(double x, double y)
{
	return x + y;
}

double sub(double x, double y)
{
	return x - y;
}

double mul(double x, double y)
{
	return x * y;
}

double div(double x, double y)
{
	return x / y;
}