C++ primer plus 第七章编程练习

4、

#include "stdafx.h"
#include<iostream>
using namespace std;
long double probability(unsigned numbers, unsigned picks);
int main()
{
double total1, choice1, total2, choice2;
cout << "Enter the total number of choices on the game card and\n"
"the number of picks allowed:\n";
while ((cin >> total1 >> choice1>>total2>>choice2) && choice1 <= total1&&choice2<=total2)
{
cout << "You have one choice in ";
cout << probability(total1, choice1)*probability(total2,choice2);
cout << " of winning.\n";
cout << "Next four 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 = result*n / p;
return result;
}

5、

/********************************************************************************************
Author:Tang Qingyun
Time:2017/03/08
From:C++ primer plus 第七章编程练习 第5题
*********************************************************************************************/

#include "stdafx.h"
#include<iostream>
using namespace std;
long long int factorial(int n);

int main()
{
int n;
long long int m;
cout << "please enter the number(q to stop):";
while (cin >> n)
{
m = factorial(n);
cout << n << "!=" << m << endl;
cout << "Next input:";
}

return 0;
}

long long int factorial(int n)
{
long long int result;
if (n < 0)
cout << "input error!";
else if (n == 0)
result=1;
else if(n > 0)
{
result = n*factorial(n - 1);
}
return result;
}

6、

/********************************************************************************************
Author:Tang Qingyun
Time:2017/03/08
From:C++ primer plus 第七章编程练习 第6题
*********************************************************************************************/

#include "stdafx.h"
#include<iostream>
using namespace std;

int Fill_array(double Arr[],int ArrSize);
void Show_array(double Arr[], int ArrSize);
void Reverse_array(double Arr[], int ArrSize);
const int max = 10;
int main()
{
double arr[max];
int n = Fill_array(arr, max);
cout << "Show the array:\n";
Show_array(arr,n);
Reverse_array(arr,n);
cout << "Show the array reversed:\n";
Show_array(arr, n);
Reverse_array(arr+1, n-2);
cout << "Show the array again:\n";
Show_array(arr, n);
return 0;
}

int Fill_array(double Arr[], int ArrSize)
{
double temp;
int i;
for (i = 0; i < ArrSize; i++)
{
cout << "please enter value#"<<i+1<<":";
cin >> temp;
if (!cin)
break;
Arr[i] = temp;
}
return i;
}
void Show_array(double Arr[], int ArrSize)
{
for (int i = 0; i < ArrSize; i++)
{
cout << "value #" << i + 1 << " =" << Arr[i]<<endl;
}
}
void Reverse_array(double Arr[], int ArrSize)
{
for (int i = 0, j = ArrSize - 1; i < j; i++, j--)
{
double temp;
temp=Arr[i];
Arr[i] = Arr[j];
Arr[j] = temp;
}
}

7、

/********************************************************************************************
Author:Tang Qingyun
Time:2017/03/08
From:C++ primer plus 第七章编程练习 第7题
*********************************************************************************************/

#include "stdafx.h"
#include<iostream>
using namespace std;
double* fill_array(double * begin, double * end);
void show_array(double * begin, double * end);
void revalue(double r, double * begin, double * end);
const int max = 5;
int main()
{
double properties[max];
double * pbegin=properties;
double * pend = fill_array(pbegin, pbegin+max);
show_array(pbegin, pend);
if ((pend - pbegin)>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, pbegin, pend);
show_array(pbegin, pend);
}
cout << "Done.\n";
cin.get();
cin.get();
return 0;
}

double* fill_array(double * begin, double * end)
{
double temp;
int i=1;
while (begin<end)
{
cout << "Enter value #" << i << ": ";
cin >> temp;
if (!cin)
{
cin.clear();
while (cin.get() != '\n')
continue;
cout << "Bad input;input process terminated.\n";
break;
}
else if (temp < 0)
break;
*begin = temp;
begin++;
i++;
}

return begin;
}
void show_array(double * begin, double * end)
{
int i = 1;
while (begin < end)
{
cout << "Property #" << i<<":$";
cout << *begin << endl;
begin++;
i++;
}
}
void revalue(double r, double * begin, double * end)
{
while (begin < end)
{
*begin *= r;
begin++;
}
}

8、a

/********************************************************************************************
Author:Tang Qingyun
Time:2017/03/09
From:C++ primer plus 第七章编程练习 第8题a
*********************************************************************************************/

#include "stdafx.h"
#include<iostream>
using namespace std;
const int seasons = 4;
const char* Snames[seasons] = { "Spring", "Summer", "Fall", "Winter" };
void fill(double arr[], int seasons);
void show(double arr[], int seasons);

int m
be41
ain()
{
double expenses[seasons];
fill(expenses,seasons);
show(expenses, seasons);
return 0;
}
void fill(double arr[], int n)
{
for (int i = 0; i < n; i++)
{
cout << "Enter " << Snames[i] << " expenses:";
cin >> arr[i];
}
}
void show(double arr[], int n)
{
double total = 0.0;
cout << "\nEXPENSES\n";
for (int i = 0; i < n; i++)
{
cout << Snames[i] << ":$" << arr[i] << endl;
total += arr[i];
}
cout << "Total Expenses:$" << total << endl;
}


8、b
/********************************************************************************************
Author:Tang Qingyun
Time:2017/03/09
From:C++ primer plus 第七章编程练习 第8题b
*********************************************************************************************/

#include "stdafx.h"
#include<iostream>
using namespace std;
const int seasons = 4;
const char* Snames[seasons] = { "Spring", "Summer", "Fall", "Winter" };
struct box
{
double expenses[seasons];
};
void fill(box *p);
void show(box a);

int main()
{
box b;
fill(&b);
show(b);
return 0;
}
void fill(box *p)
{
for (int i = 0; i < seasons; i++)
{
cout << "Enter " << Snames[i] << " expenses:";
cin >> p->expenses[i];
}
}
void show(box a)
{
double total = 0.0;
cout << "\nEXPENSES\n";
for (int i = 0; i < seasons; i++)
{
cout << Snames[i] << ":$" << a.expenses[i] << endl;
total += a.expenses[i];
}
cout << "Total Expenses:$" << total << endl;
}


9、
/********************************************************************************************
Author:Tang Qingyun
Time:2017/03/09
From:C++ primer plus 第七章编程练习 第9题
*********************************************************************************************/

#include "stdafx.h"
#include<iostream>
#include<string>
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)
{
int i;
for (i = 0; i < n; i++)
{
cout << "Please enter the student "<<i+1<<" 's name:";
char temp1[SLEN];
cin.getline(temp1, SLEN);
if (!strcmp(temp1,""))
break;
strcpy_s(pa[i].fullname ,temp1);

cout << "Please enter the student " << i + 1 << " 's hobby:";
char temp2[SLEN];
cin.getline(temp2, SLEN);
strcpy_s(pa[i].hobby, temp2);

cout << "Please enter the student " << i + 1 << " 's ooplevel:";
int temp3;
cin >> temp3;
pa[i].ooplevel = temp3;
cin.get();
}

return i;
}

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

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

void display3(const student pa[], int n)
{
for (int i = 0; i < n; i++)
{
cout << "the "<<i+1<<" student's fullname:" << pa[i].fullname<<endl;
cout << "the " << i+1 << " student's hobby:" << pa[i].hobby<<endl;
cout << "the " << i+1 << " student's ooplevel:" << pa[i].ooplevel<<endl;
}
}

10、
/********************************************************************************************
Author:Tang Qingyun
Time:2017/03/09
From:C++ primer plus 第七章编程练习 第10题
*********************************************************************************************/

#include "stdafx.h"
#include<iostream>
#include<string>
using namespace std;

double add(double x, double y);
double sub(double x, double y);
double mean(double x, double y);
double calculate(double x, double y, double(*pf)(double, double));
string name[3] = { "add", "sub", "mean" };

int main()
{
double a, b;
double(*pf[3])(double, double) = { add, sub, mean };
cout << "Enter pairs of numbers(q to quit):";
while (cin >> a >> b)
{
for (int i = 0; i < 3; i++)
{
cout << a << " "<<name[i]<<" " << b << " =" << calculate(a, b, pf[i]) << endl;
}
cout << "Enter pairs of numbers(q to quit):";
}
return 0;
}

double add(double x, double y)
{
return x + y;
}
double sub(double x, double y)
{
return x - y;
}
double mean(double x, double y)
{
return (x + y) / 2.0;
}
double calculate(double x, double y, double(*pf)(double, double))
{
return (*pf)(x, y);
}