//本博主所写的代码仅为阅读者提供参考；
//若有不足之处请提出，博主会尽所能修改；
//附上课后编程练习题目；
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//7.13 - 1.cpp
#include <iostream>
using namespace std;
double harmonic_mean(double x, double y);
int main()
{
double a, b;
cout << "Please enter two numbers (0 to quit): ";
while (cin >> a >> b && a != 0 && b != 0)
{
cout << "The harmonic mean of " << a;
cout << " and " << b << " is ";
cout << harmonic_mean(a, b) << endl;
cout << "Next two numbers (0 to quit): ";
}
cout << "Bye." << endl;
return 0;
}
double harmonic_mean(double x, double y)
{
return 2.0 * x * y / (x + y);
}
//-------------
//7.13 - 2.cpp
#include <iostream>
using namespace std;
int initialize_array(double arr[], int n);
void show_array(const double arr[], int n);
void count_average(const double arr[], int n);
const int ArSize = 10;
int main()
{
int n;
double golf[ArSize];
n = initialize_array(golf, ArSize);
show_array(golf, n);
count_average(golf, n);
cout << "Bye." << endl;
return 0;
}
int initialize_array(double arr[], int n)
{
int i = 0;
cout << "You can enter up to " << ArSize;
cout << " golf scores (q to terminate)." << endl;
cout << "Golf scores #1: ";
while (i < n && cin >> arr[i])
{
if (++i < ArSize)
{
cout << "Golf scores #" << i + 1 << ": ";
}
}
return i;
}
void show_array(const double arr[], int n)
{
cout << "All golf scores:" << endl;
for (int i = 0; i < n; i++)
{
cout << arr[i] << ' ';
}
cout.put('\n');
return;
}
void count_average(const double arr[], int n)
{
double aver = 0.0;
for (int i = 0; i < n; i++)
{
aver += arr[i];
}
aver /= n;
cout << "Average golf scores: " << aver << endl;
return;
}
//-------------
//7.13 - 3.cpp
#include <iostream>
using namespace std;
struct box
{
char maker[40];
float height;
float width;
float length;
float volume;
};
void value_show_box(box temp);
void address_show_box(box *temp);
int main()
{
box smallbox = {
"Cute box", 20, 10, 30, 50};
value_show_box(smallbox);
address_show_box(&smallbox);
value_show_box(smallbox);
return 0;
}
void value_show_box(box temp)
{
cout << "\nBox informations: " << endl;
cout << "Name: " << temp.maker << endl;
cout << "height: " << temp.height << endl;
cout << "width: " << temp.width << endl;
cout << "length: " << temp.length << endl;
cout << "volume: " << temp.volume << endl;
return;
}
void address_show_box(box *temp)
{
temp->volume = temp->height * temp->width * temp->length;
return;
}
//-------------
//7.13 - 4.cpp
#include <iostream>
using namespace std;
long double probability(unsigned numbers, unsigned picks);
int main()
{
unsigned total, choices, temp;
cout << "Enter the total number of choices on the game card and\n";
cout << "the number of picks allowed and the second section(<= total number):" << endl;
while ((cin >> total >> choices >> temp) && choices <= total && temp <= total)
{
cout << "You have one chance in ";
cout << probability(total, choices) * probability(temp, 1); //2个选择的乘积;
cout << " of winning.\n";
cout << "Next three numbers (q to quit): ";
}
cout << "bye!\n";
return 0;
}
long double probability(unsigned numbers, unsigned picks)
{
long double result = 1.0;
long double n;
unsigned p;
for (n = numbers, p = picks; p > 0; n--, p--)
{
result *= n / p;
}
return 1.0 / result; //源程序7.4中奖概率不对,应该是result计算完之后的倒数,在此进行改正;
}
//-------------
//7.13 - 5.cpp
#include <iostream>
using namespace std;
long double factorial(long double n);
int main()
{
long double temp;
cout << "Please enter a number(<0 or q to quit): ";
while (cin >> temp && temp >= 0)
{
cout << temp << "! = " << factorial(temp) << endl;
cout << "Next number(<0 or q to quit): ";
}
cout << "Bye." << endl;
return 0;
}
long double factorial(long double n)
{
if (0 == n)
{
return 1;
}
else
{
return n * factorial(n - 1);
}
}
//-------------
//7.13 - 6.cpp
#include <iostream>
using namespace std;
int Fill_array(double arr[], int n);
void Show_array(const double arr[], int n);
void Reverse_average(double arr[], int n);
const int ArSize = 10;
int main()
{
int n;
double arr[ArSize];
n = Fill_array(arr, ArSize);
Show_array(arr, n);
Reverse_average(arr, n);
Show_array(arr, n);
Reverse_average(arr + 1, n - 2);
Show_array(arr, n);
cout << "Bye." << endl;
return 0;
}
int Fill_array(double arr[], int n)
{
int i = 0;
cout << "You can enter up to " << ArSize;
cout << " numbers (q to terminate)." << endl;
cout << "Number #1: ";
while (i < n && cin >> arr[i])
{
if (++i < ArSize)
{
cout << "Number #" << i + 1 << ": ";
}
}
return i;
}
void Show_array(const double arr[], int n)
{
cout << "All numbers:" << endl;
for (int i = 0; i < n; i++)
{
cout << arr[i] << ' ';
}
cout.put('\n');
return;
}
void Reverse_average(double arr[], int n)
{
double temp;
for (int i = 0; i < n / 2; i++)
{
temp = arr[n - 1 - i];
arr[n - 1 - i] = arr[i];
arr[i] = temp;
}
return;
}
//-------------
//7.13 - 7.cpp
#include <iostream>
using namespace std;
const int Max = 5;
double *fill_array(double *begin, double *end);
void show_array(const double *begin, double *end);
void revalue(double r, double *begin, double *end);
int main()
{
double properties[Max];
double *size = fill_array(properties, properties + Max);
show_array(properties, size);
if (size - properties > 0)
{
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, size);
show_array(properties, size);
}
cout << "Done.\n";
return 0;
}
double *fill_array(double *begin, double *end)
{
int i;
double temp;
double *ptr;
for (i = 0, ptr = begin; ptr < end; i++, ptr++)
{
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;
}
*ptr = temp;
}
return begin + i;
}
void show_array(const double *begin, double *end)
{
int i;
const double *ptr;
for (i = 0, ptr = begin; ptr < end; i++, ptr++)
{
cout << "Property #" << (i + 1) << ": $";
cout << *ptr << endl;
}
return;
}
void revalue(double r, double *begin, double *end)
{
for (double temp = begin; temp < end; temp++)
{
*temp *= r;
}
return;
}
//-------------
//7.13 - 8(a).cpp
#include <iostream>
const int Seasons = 4;
const char *Snames[Seasons] = {
"Spring", "Summer", "Fall", "Winter"};
void fill(double pa[], int n);
void show(const double pa[], int n);
int main()
{
double expenses[Seasons];
fill(expenses, Seasons);
show(expenses, Seasons);
return 0;
}
void fill(double pa[], int n)
{
for (int i = 0; i < n; i++)
{
std::cout << "Enter " << Snames[i] << " expenses: ";
std::cin >> pa[i];
}
return;
}
void show(const double pa[], int n)
{
double total = 0.0;
std::cout << "\nEXPENSES\n";
for (int i = 0; i < n; i++)
{
std::cout << Snames[i] << ": $" << pa[i] << '\n';
total += pa[i];
}
std::cout << "Total: $" << total << '\n';
return;
}
//-------------
//7.13 - 8(b).cpp
#include <iostream>
const int Seasons = 4;
const char *Snames[Seasons] = {
"Spring", "Summer", "Fall", "Winter"};
struct spending
{
double expenses[Seasons];
};
void fill(spending *temp);
void show(spending *temp);
int main()
{
spending temp;
fill(&temp);
show(&temp);
return 0;
}
void fill(spending *temp)
{
for (int i = 0; i < Seasons; i++)
{
std::cout << "Enter " << Snames[i] << " expenses: ";
std::cin >> temp->expenses[i];
}
return;
}
void show(spending *temp)
{
double total = 0.0;
std::cout << "\nEXPENSES\n";
for (int i = 0; i < Seasons; i++)
{
std::cout << Snames[i] << ": $" << temp->expenses[i] << '\n';
total += temp->expenses[i];
}
std::cout << "Total: $" << total << '\n';
return;
}
//-------------
//7.13 - 9.cpp
#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;
cout << "Done\n";
return 0;
}
int getinfo(student pa[], int n)
{
cout << "You can enter up to " << n;
cout << " students' messages (enter to terminate)." << endl;
for (int i = 0; i < n; i++)
{
cout << "Student #" << i + 1 << ": " << endl;
cout << "Enter the fullname(a blank line to quit): ";
cin.getline(pa[i].fullname, SLEN);
if ('\0' == pa[i].fullname[0]) //题目要求空行结束输入;
{
break;
}
cout << "Enter the hobby: ";
cin.getline(pa[i].hobby, SLEN);
cout << "Enter the ooplevel: ";
while (!(cin >> pa[i].ooplevel))
{
cin.clear();
while (cin.get() != '\n')
continue;
cout << "Please enter an number: ";
}
cin.get(); //吸收正确输入时的换行符;
}
return i;
}
void display1(student st)
{
cout << "\nName: " << st.fullname << endl;
cout << "Hobby: " << st.hobby << endl;
cout << "Ooplevel: " << st.ooplevel << endl;
return;
}
void display2(const student *ps)
{
cout << "\nName: " << ps->fullname << endl;
cout << "Hobby: " << ps->hobby << endl;
cout << "Ooplevel: " << ps->ooplevel << endl;
return;
}
void display3(const student pa[], int n)
{
if (n > 0)
{
cout << "\nAll students' information:" << endl;
for (int i = 0; i < n; i++)
{
cout << "Name: " << pa[i].fullname << endl;
cout << "Hobby: " << pa[i].hobby << endl;
cout << "Ooplevel: " << pa[i].ooplevel << endl;
}
}
return;
}
//-------------
//7.13 - 10.cpp
#include <iostream>
using namespace std;
double calculate(double a, double b, double (*p)(double a, double b));
double add(double a, double b);
double subtract(double a, double b);
double multiply(double a, double b);
int main()
{
double a, b;
double (*pf[3])(double a, double b) = {
add, subtract, multiply};
cout << "Enter two numbers (q to quit): ";
while (cin >> a >> b)
{
for (int i = 0; i < 3; i++)
{
switch (i)
{
case 0:
{
cout << "The " << a << " + " << b << " answer is: " << (*pf[i])(a, b) << endl;
break;
}
case 1:
{
cout << "The " << a << " - " << b << " answer is: " << (*pf[i])(a, b) << endl;
break;
}
case 2:
{
cout << "The " << a << " * " << b << " answer is: " << (*pf[i])(a, b) << endl;
break;
}
}
}
cout << "Next two numbers (q to quit): ";
}
cout << "Done!" << endl;
return 0;
}
double calculate(double a, double b, double (*p)(double a, double b))
{
return (*p)(a, b);
}
double add(double a, double b)
{
return a + b;
}
double subtract(double a, double b)
{
return a - b;
}
double multiply(double a, double b)
{
return a * b;
}
//-------------
//8.8 - 1.cpp
#include <iostream>
using namespace std;
void print_string(const char *str, int i = 0);
int main()
{
const char *str = "This is a test.";
cout << "Only one parameter, print 1 times:" << endl;
print_string(str);
cout << "Having two parameter can print arbitrary times:" << endl;
print_string(str, 3);
cout << "Bye." << endl;
return 0;
}
void print_string(const char *str, int i)
{
cout << str << endl;
if (i > 1)
{
print_string(str, i - 1); //递归进行输出i次str字符串;
}
return;
}
//-------------
//8.8 - 2.cpp
#include <iostream>
#include <cstring>
struct CandyBar
{
char brand[20];
double weight;
int calorie;
};
void initialize_candybar(CandyBar &temp, const char *str = "Millennium Munch", double w = 2.85, int c = 350);
void show_candybar(const CandyBar &temp);
int main()
{
CandyBar mycandybar;
initialize_candybar(mycandybar);
show_candybar(mycandybar);
return 0;
}
void initialize_candybar(CandyBar &temp, const char *str, double w, int c)
{
strcpy(temp.brand, str);
temp.weight = w;
temp.calorie = c;
return;
}
void show_candybar(const CandyBar &temp)
{
using namespace std;
cout << "Output CandyBar information:" << endl;
cout << "Brand: " << temp.brand << endl;
cout << "Weight: " << temp.weight << endl;
cout << "Calorie: " << temp.calorie << endl;
return;
}
//-------------
//8.8 - 3.cpp
#include <iostream>
#include <cctype>
#include <string>
using namespace std;
void print_upper_string(string &str);
int main()
{
string str;
cout << "Enter a string (q to quit): ";
while (getline(cin, str) && str != "q")
{
print_upper_string(str);
cout << str << endl;
cout << "Next string (q to quit): ";
}
cout << "Bye." << endl;
return 0;
}
void print_upper_string(string &str)
{
for (int i = 0; i < str.size(); i++)
{
str[i] = toupper(str[i]);
}
return;
}
//-------------
//8.8 - 4.cpp
#include <iostream>
#include <cstring>
using namespace std;
struct stringy
{
char *str;
int ct;
};
void set(stringy &stry, const char *str);
void show(stringy &stry, int i = 1);
void show(const char *str, int i = 1);
int main()
{
stringy beany;
char testing[] = "Reality isn't what it used to be.";
set(beany, testing);
show(beany);
show(beany, 2);
testing[0] = 'D';
testing[1] = 'u';
show(testing);
show(testing, 3);
delete[] beany.str; //题目中未释放new分配的内存,在此添加释放内存语句;
show("Done!");
return 0;
}
void set(stringy &stry, const char *str)
{
stry.str = new char[strlen(str) + 1];
strcpy(stry.str, str);
return;
}
void show(stringy &stry, int i)
{
cout << stry.str << endl;
if (i > 1)
{
for (int k = 0; k < i - 1; k++)
{
cout << stry.str << endl;
}
}
return;
}
void show(const char *str, int i)
{
cout << str << endl;
if (i > 1)
{
for (int k = 0; k < i - 1; k++)
{
cout << str << endl;
}
}
return;
}
//-------------
//8.8 - 5.cpp
#include <iostream>
using namespace std;
template <typename T>
T max5(const T *array);
int main()
{
int test1[5] = {
1, 3, 5, 7, 9};
double test2[5] = {
10.0, 20.0, 15.0, 12.0, 30.0};
cout << "The max of int array is: " << max5(test1) << endl;
cout << "The max of double array is: " << max5(test2) << endl;
return 0;
}
template <typename T>
T max5(const T *array)
{
T temp = array[0];
for (int i = 1; i < 5; i++)
{
if (temp < array[i])
{
temp = array[i];
}
}
return temp;
}
//-------------
//8.8 - 6.cpp
#include <iostream>
#include <cstring>
using namespace std;
template <typename T>
T maxn(T *arr, int n);
template <>
const char *maxn(const char *str[], int n);
int main()
{
int test1[6] = {
1, 3, 5, 7, 9, 11};
double test2[4] = {
10.0, 20.0, 15.0, 12.0};
const char *test3[5] = {
"123", "12345", "123456", "abcdefg", "xio"};
cout << "The max of int array is: " << maxn(test1, 6) << endl;
cout << "The max of double array is: " << maxn(test2, 4) << endl;
cout << "The max of string array is: " << maxn(test3, 5) << endl;
return 0;
}
template <typename T>
T maxn(T *arr, int n)
{
T temp = arr[0];
for (int i = 0; i < n; i++)
{
if (temp < arr[i])
{
temp = arr[i];
}
}
return temp;
}
template <>
const char *maxn(const char *str[], int n)
{
const char *temp = *str;
for (int i = 1; i < n; i++)
{
if (strlen(temp) < strlen(str[i]))
{
temp = str[i];
}
}
return temp;
}
//-------------
//8.8 - 7.cpp
#include <iostream>
template <typename T>
T SumArray(T arr[], int n);
template <typename T>
T SumArray(T *arr[], int n);
struct debts
{
char name[50];
double amount;
};
int main()
{
using namespace std;
int things[6] = {
13, 31, 103, 301, 310, 130};
debts mr_E[3] =
{
{
"Ima Wolfe", 2400.0},
{
"Ura Foxe", 1300.0},
{
"Iby Stout", 1800.0}
};
double *pd[3];
for (int i = 0; i < 3; i++)
{
pd[i] = &mr_E[i].amount;
}
cout << "Listing Mr. E's total of things:" << endl;
cout << SumArray(things, 6) << endl;
cout << "Listing Mr. E's total of debts:" << endl;
cout << SumArray(pd, 3) << endl;
return 0;
}
template <typename T>
T SumArray(T arr[], int n)
{
using namespace std;
double sum = 0.0;
for (int i = 0; i < n; i++)
{
sum += arr[i];
}
return sum;
}
template <typename T>
T SumArray(T *arr[], int n)
{
using namespace std;
double sum = 0.0;
for (int i = 0; i < n; i++)
{
sum += *arr[i];
}
return sum;
}
//-------------
//------------------------------------------2020年9月27日 ----------------------------------------------;