C++primer plus 第七章习题（自己写的，欢迎指正）

#include<iostream>
#include<stdlib.h>

//第七章
using namespace std;

double aver(const int *x, const int *y);
int main()
{
int x, y;
cout << "Please enter two figures:";
cin >> x >> y;
double res = aver(&x, &y);
cout << "Your result is:" << res << endl;
system("pause");
return 0;
}

double aver(const int *x,const int *y)
{
double result = 0;
result = 2.0*(*x)*(*y) / (*x + *y);
return result;
}

#include<iostream>
#include<stdlib.h>

//第七章
using namespace std;
const int Max = 10;

int fill(double arr[],int len);
double deal(double arr[], int len);
void display(double arr[], int len,double sum);
int main()
{
double arr[Max];
int x;
double y;
x = fill(arr, Max);
y = deal(arr, x);
display(arr, x, y);
system("pause");
return 0;
}

int fill(double arr[], int len)
{
int i;
double num;
for (i = 0; i < len; i++)
{
cout << "Please enter your figures:";
while (!(cin >> num))
{
cin.clear();
while (cin.get() != '\n')
continue;
cout << "Bad input!" << endl;
break;
}
if (num < 0)
{
break;
}
arr[i] = num;
}
return i;
}

double deal(double arr[], int len)
{
double sum=0;
for (int i = 0; i < len; i++)
{
sum += arr[i];
}
return sum;
}
void display(double arr[], int len, double sum)
{
for (int i = 0; i < len; i++)
{
cout << "Grade:" << arr[i] << " ";
}
cout << endl;
cout << "Total grade:" << sum << endl;
cout << "Average grade:" << sum / len << endl;
}

#include<iostream>
#include<stdlib.h>

//第七章
using namespace std;
const int Max = 10;

struct box
{
char maker[40];
float height;
float width;
float length;
float volume;
};
box fill();
void show(box b);
void fill(box *b);
void show(box *b);
int main()
{
box a;
a = fill();
show(a);
box c;
/*fill(&c);
show(&c);*/
system("pause");
return 0;
}
box fill()
{
box b;
cout << "Please enter your maker:";
cin >> b.maker;
cout << "Please enter your height:";
cin >> b.height;
cout << "Please enter your width:";
cin >> b.width;
cout << "Please enter your length:";
cin >> b.length;
cout << "Please enter your volume:";
cin >> b.volume;
return b;
}
void show(box b)
{
cout << "Your maker:" << b.maker << endl;
cout << "Your height:" << b.height << endl;
cout << "Your width:" << b.width << endl;
cout << "Your length:" << b.length << endl;
cout << "Your volume:" << b.volume << endl;

}

void fill(box *b)
{
cout << "Please enter your maker:";
cin >> b->maker;
cout << "Please enter your height:";
cin >> b->height;
cout << "Please enter your width:";
cin >> b->width;
cout << "Please enter your length:";
cin >> b->length;
cout << "Please enter your volume:";
cin >> b->volume;

}
void show(box *b)
{
cout << "Your maker:" << b->maker << endl;
cout << "Your height:" << b->height << endl;
cout << "Your width:" << b->width << endl;
cout << "Your length:" << b->length << endl;
cout << "Your volume:" << b->volume << endl;
}

#include<iostream>
#include<stdlib.h>
#define ui unsigned int
//第七章
using namespace std;
const int Max = 10;
struct area
{
ui ar1;
ui ar2;
};

void probiba(area ar1, area ar2);

int main()
{
area are1, are2;
cout << "Please enter first ar1 and ar2:";
cin >> are1.ar1 >> are1.ar2;
cout << "Please enter second ar1 and ar2:";
cin >> are2.ar1 >> are2.ar2;
probiba(are1, are2);
system("pause");
return 0;
}

void probiba(area are1, area are2)
{
long double res1 = 1.0,res2=1.0;
ui i, j;
for (i = are1.ar1,j=are1.ar2; j>0; i--,j--)
{
res1 = res1*i/j;
}
cout << "pro1:" << res1 << endl;
for (i = are2.ar1,j = are2.ar2; j>0; i--, j--)
{
res2 = res2*i / j;
}
cout << "pro2:" << res2 << endl;
cout << "End pro:" << res1*res2 << endl;
}

#include<iostream>
#include<stdlib.h>
#define ui unsigned int
//第七章
using namespace std;

long long jiecheng(int x);
int main()
{
int num;
cout << "Please enter your num:";
cin >> num;
long long res=jiecheng(num);
cout << "Result:" << res << endl;
system("pause");
return 0;
}
long long jiecheng(int x)
{
if (x == 1 || x == 0)
return 1;
else
return x*jiecheng(x-1);

}

#include<iostream>
#include<stdlib.h>
//第七章
const int Size = 10;
using namespace std;
int fillnum(double arry[], int size);
void show(double array[], int size);
void reserve(double array[], int size);
int main()
{
double array[Size];
int i = fillnum(array, Size);
show(array, i);
reserve(array, i);
show(array, i);
system("pause");
return 0;
}

int fillnum(double arry[], int size)
{
int i;
for ( i = 0; i < size; i++)
{
cout << "Please enter your number:";
if(!(cin >> arry[i]))
break;
}
return i;
}
void show(double array[], int size)
{
cout << "The number of array:";
for (int i = 0; i < size; i++)
{
cout << array[i] << " ";
}
cout << endl;
}
void reserve(double array[], int size)
{
int j;
for (int i = 0,j=size-1; i < size/2; i++,j--)
{
double temp = array[i];
array[i] = array[j];
array[j] = temp;
}
}

#include<iostream>
#include<stdlib.h>
//第七章
const int Size = 5;
using namespace std;
double * fillnum(double arry[], int size);
void show(double array[], double *);
void revalue(double array[], double *,double r);
int main()
{
double array[Size];
double * i = fillnum(array, Size);
show(array, i);
double r;
cout << "Please enter your r:";
cin >> r;
revalue(array, i,r);
show(array, i);
system("pause");
return 0;
}

double* fillnum(double arry[], int size)
{
int i;
for (i = 0; i < size; i++)
{
cout << "Please enter your number:";
if (!(cin >> arry[i]))
{
cin.get();
break;
}
else if (arry[i] < 0)
{
cin.get();
break;
}
}
return &arry[i];
}
void show(double array[], double *end)
{
cout << "The number of array:";
double * i;
for (i = array; i !=end; i++)
{
cout << *i << " ";
}
cout << endl;
}
void revalue(double array[], double *end,double r)
{
double *i;
for (i = array; i != end; i++)
{
(*i) *= r;
}
}

#include<iostream>
#include<stdlib.h>
//第七章
const int Size = 4;
const char *seasons[4] = { "spring", "summer", "autumn", "winter" };
using namespace std;
double * fillnum(double arry[], int size);
void show(double array[], double *);
int z;
int main()
{
double array[Size];
double * i = fillnum(array, Size);
show(array, i);
system("pause");
return 0;
}

double* fillnum(double arry[], int size)
{
for (z = 0; z < size; z++)
{
cout << "Please enter "<<seasons[z]<<" expense:";
if (!(cin >> arry[z]))
{
cin.get();
break;
}
else if (arry[z] < 0)
{
cin.get();
break;
}
}
return &arry[z];
}
void show(double array[], double *end)
{
double * i;
int j = 0;
for (i = array,j=0; i != end,j<z; i++,j++)
{
cout << seasons[j] << " espense:";
cout << *i <<endl;
}
}

#include<iostream>
#include<stdlib.h>
//第七章
const int SLEN = 30;
using namespace std;
struct student
{
char fullname[SLEN];
char hobby[SLEN];
int  ooplevel;
};
int getinfo(student pa[], int n);
void display1(student st);
void display2(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";
system("pause");
return 0;
}

int getinfo(student pa[], int n)
{
int i;
for (i = 0; i < n; i++)
{
cout << "Please your name:";
cin >> pa[i].fullname;
if (pa[i].fullname == " ")
break;
cout << "Please your hobby:";
cin >> pa[i].hobby;
cout << "Please your opplevel:";
cin >> pa[i].ooplevel;
}
return i;
}
void display1(student st)
{
cout << "Your name is:"<<st.fullname<<endl;
cout << "Your hobby is:" << st.hobby << endl;
cout << "Your opplevel is:" << st.ooplevel << endl;
}
void display2(student *ps)
{
cout << "Your name is:" << ps->fullname << endl;
cout << "Your hobby is:" << ps->hobby << endl;
cout << "Your opplevel is:" << ps->ooplevel << endl;
}
void display3(const student pa[], int n)
{
for (int i = 0; i < n; i++)
{
cout << "Your name is:" << (pa + i)->fullname << endl;
cout << "Your hobby is:" << (pa + i)->hobby << endl;
cout << "Your opplevel is:" << (pa + i)->ooplevel << endl;
}
}

#include<iostream>
#include<stdlib.h>
//第七章
typedef double(*pf)(double, double);
using namespace std;
double calculate(double, double, pf);
double add(double, double);
double sub(double, double);
double mut(double, double);
double div(double, double);
int main()
{
int num1, num2;
pf ca[4]= {add,sub,div,mut};
char *cal[] = { "add", "sub", "div", "mut" };
cout << "Please enter two figures:";
cin >> num1 >> num2;
for (int i = 0; i < 3; i++)
{
double x = calculate(num1, num2,ca[i]);
cout << cal[i] <<":"<< x << endl;
}
system("pause");
return 0;
}
double calculate(double x, double y, pf ca)
{
return (*ca)(x, y);
}
double add(double x, double y)
{
return x + y;
}
double sub(double x, double y)
{
return x - y;
}
double mut(double x, double y)
{
return x*y;
}
double div(double x, double y)
{
return x / y;
}