【学习C++】C++ Primer Plus （第六版）第七章编程练习6-10

6.

#include <iostream>

using namespace std;
int Fill_array(double [], int size);
void Show_array(double [], int size);
void Reverse_array(double [], int size);
int main()
{
	int size,rsize;
	cin >> size;
	double *arr = new double [size];
	rsize = Fill_array(arr, size);
	Show_array(arr, rsize);
	Reverse_array(arr, rsize);
	Show_array(arr, rsize);
	cin.get();
	cin.get();
	return 0;
}
int Fill_array(double arr [], int size){
	int i;
	for (i = 0; i < size; i++)
	{
		cin >> arr[i];
		if (!cin)
			break;
	}
	return i;
}
void Show_array(double arr [], int size){
	for (int i = 0; i < size; i++){
		cout << "arr[" << i << "] = " << arr[i] << endl;
	}
	cout << "\n";
}
void Reverse_array(double arr [], int size){
	double m;
	int begin, end;
	for (begin = 1, end = size - 2; begin < end; begin++, end--){
		m = arr[begin];
		arr[begin] = arr[end];
		arr[end] = m;
	}
}

7.

#include <iostream>
const int Max = 5;
using namespace std;
double * fill_array(double *begin, double *end);
void show_array(const double *begin,const double *end);
void revalue(double r, double *begin, double *end);
int main()
{
	double properties[Max];
	double *end = fill_array(properties, properties + Max);
	show_array(properties, end+1);
	if (end != properties){
		cout << "Enter revaluation factor: ";
		double factor;
		while (!(cin >> factor)){
			cin.clear();
			while (cin.get() != '\n')
				continue;
			cout << "Bad input;Please enter a number: ";
		}
		revalue(factor, properties, end+1);
		show_array(properties, end+1);
	}
	cout << "Done.\n";
	cin.get();
	cin.get();
	return 0;
}
double * fill_array(double *begin, double *end){
	double temp;
	double *m;
	int i;
	for (m = begin,i=0; m != end; m++,i++){
		cout << "Enter value #" << (i + 1) << ": ";
		cin >> temp;
		if (!cin){
			cin.clear();
			while (cin.get() != '\n')
				continue;
			cout << "Bad input;input process terminated.\n";
			break;
		}
		else if (temp < 0)
			break;
		*m = temp;
	}
	return m-1;
}
void show_array(const double *begin, const double *end){
	int i;
	const double *m;
	for (m = begin, i = 0; m != end; m++, i++){
		cout << "Property #" << (i + 1) << ": $";
		cout << *m<<endl;
	}
}
void revalue(double r, double *begin, double *end){
	double *m;
	for (m = begin; m != end; m++)
		*m = (*m)*r;
}

8.a

#include <iostream>
using namespace std;
const int Seasons = 4;
const char *Snames[Seasons] = { "Spring", "summer", "Fall", "Winter" };
void fill(double pa[],int n);
void show(const double da[],int n);
int main()
{
	double expenses[Seasons];
	fill(expenses,Seasons);
	show(expenses,Seasons);
	cin.get();
	cin.get();
	return 0;
}
void fill(double pa[],int n){
	for (int i = 0; i < n; i++){
		cout << "Enter " << Snames[i] << " expenses:";
		cin >> pa[i];
	}
}
void show(const double da [], int n){
	double total = 0;
	cout << "EXPENSES\n";
	for (int i = 0; i < n; i++){
		cout << Snames[i] << ": $" << da[i] << endl;
		total += da[i];
	}
	cout << "Total Expenses : $" << total << endl;
}

8.b

#include <iostream>
using namespace std;
const int Seasons = 4;
const char *Snames[Seasons] = { "Spring", "summer", "Fall", "Winter" };
struct Expenses{
	double exp[Seasons];
};
void fill(Expenses *);
void show(Expenses);
int main()
{
	Expenses a;
	fill(&a);
	show(a);
	cin.get();
	cin.get();
	return 0;
}
void fill(Expenses *a){
	for (int i = 0; i < Seasons; i++){
		cout << "Enter " << Snames[i] << " expenses:";
		cin >> a->exp[i];
	}
}
void show(Expenses a){
	double total = 0;
	cout << "EXPENSES\n";
	for (int i = 0; i < Seasons; i++){
		cout << Snames[i] << ": $" << a.exp[i] << endl;
		total += a.exp[i];
	}
	cout << "Total Expenses : $" << total << endl;
}

9.

#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 << "Enter class size: ";
	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);
	delete [] ptr_stu;
	cin.get();
	cin.get();
	return 0;
}
int getinfo(student pa [], int n){
	int i;
	for (i = 0; i < n; i++){
		cin.getline(pa[i].fullname, SLEN);
		if ((pa[i].fullname)[0] == '\0'){
			break;
		}
		cin.getline(pa[i].hobby, SLEN);
		cin >> pa[i].ooplevel;
		cin.get();
	}
	return i;
}
void display1(student st){
	cout << "name: " << st.fullname<<endl;
	cout << "hobby: " << st.hobby<<endl;
	cout << "ooplevel: " << st.ooplevel << endl;
}
void display2(const student * ps){
	cout << "name: " << ps->fullname<<endl;
	cout << "hobby: " << ps->hobby << endl;
	cout << "ooplevel: " << ps->ooplevel << endl;
}
void display3(const student pa [], int n){
	int i;
	for (i = 0; i < n; i++){
		cout << "name: " << pa[i].fullname << endl;
		cout << "hobby: " << pa[i].hobby << endl;
		cout << "ooplevel: " << pa[i].ooplevel << endl;
	}
}

10.

#include <iostream>
using namespace std;
double add(double x, double y);
double max(double x, double y);
double min(double x, double y);
double calculate(double x, double y, double(*p)(double a, double b));
int main()
{
	double x,y;
	double q;
	double (*pf[3])(double, double) = {add,max,min};
	while (cin >> x >> y){
		for (int i = 0; i < 3; i++){
			q = calculate(x, y, *pf[i]);
			if (i==0)
				cout << "the sum of two numbers: " << q << endl;
			else if (i==1)
				cout << "the max number of the two numbers; " << q << endl;
			else if (i==2)
				cout << "the min number of the two numbers; " << q << endl;
		}
	}
	cin.get();
	cin.get();
	return 0;
}
double add(double x, double y){
	return x + y;
}
double calculate(double x, double y, double(*p)(double a, double b)){
	double m;
	m = (*p)(x, y);
	return m;
}
double max(double x, double y){
	return x > y ? x : y;
}
double min(double x, double y){
	return x < y ? x : y;
}