c++ primer plus 习题答案(3)

p296.3

 #include<iostream>
 #include<cstdlib>
 #include<string>
 #include<cstring>
 #include<new>
 using namespace std;
 struct chaff
 {
     char dross[];
     int slag;
 };
 void setarray(chaff *pt);
 void showarray(chaff *pt);

 int main(){
     char buffer[];
     chaff ar[], *pt;
     pt = new(buffer)chaff[];
     setarray(pt);
     showarray(pt);
     system("pause");
     return ;
 }

 void setarray(chaff *pt){
     int i;
     char adross[], pdross[], ch;
     cout << "enter a line\n";
     cin.get(adross, );
     while (cin){
         cin.get(ch);
         while (ch != '\n')
             cin.get(ch);
         break;
     }
     strcpy(pt->dross, adross);
     cout << "enter another line\n";
     cin.get(pdross, );
     while (cin){
         cin.get(ch);
         while (ch != '\n')
             cin.get(ch);
         break;
     }
     strcpy((pt + )->dross, pdross);
     cout << "enter two integer\n";
     cin >> pt->slag;
     cin >> (pt + )->slag;
     cin.get();
 }

 void showarray(chaff *pt){
     cout << pt->dross << " " <<
         pt->slag << endl <<
         (pt + )->dross << " " <<
         (pt + )->slag << endl;
 }

p296.4

 sales.cpp

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

 void SALES::setsales(Sales &s, const double ar[], int n){
     int num, i, sum=;
     if (n <= QUARTERS)
         num = n;
     else num = QUARTERS;
     for (i = ; i < num; i++){
         s.sales[i] = ar[i];
         sum += s.sales[i];
     }
     s.average = sum / num;
     s.max = s.sales[];
     s.min = s.sales[];
     for (i = ; i < num; i++){
         if (s.max < s.sales[i])
             s.max = s.sales[i];
         if (s.min>s.sales[i])
             s.min = s.sales[i];
     }
 }

 void SALES::setsales(Sales &s){
     cout << "enter double into an array\n";
     int i;
     double sum = ;
     for (i = ; i < QUARTERS; i++){
         cin >> s.sales[i];
         sum += s.sales[i];
     }
     s.average = sum / QUARTERS;
     s.max = s.sales[];
     s.min = s.sales[];
     for (i = ; i < QUARTERS; i++){
         if (s.max < s.sales[i])
             s.max = s.sales[i];
         if (s.min>s.sales[i])
             s.min = s.sales[i];
     }
 }

 void SALES::showsales(const Sales & s){
     for (int i = ; i < QUARTERS; i++)
         cout << s.sales[i] << " ";
     cout << "average is " << s.average << endl <<
         "max is " << s.max << endl <<
         "min is " << s.min << endl;
 }

 驱动程序

 #include<iostream>
 #include<cstdlib>
 #include<string>
 #include<cstring>
 #include"sales.h"
 using namespace std;

 int main(){
     cout << "enter a number you want to fill the array\n";
     int n, i;
     cin >> n;
     double *ar = new double[n+];
     cout << "enter an double array\n";
     for (i = ; i < n; i++)
         cin >> ar[i];
     SALES::Sales ex1, ex2;
     SALES::setsales(ex1, ar, n);
     SALES::setsales(ex2);
     SALES::showsales(ex1);
     SALES::showsales(ex2);
     delete[]ar;
     system("pause");
     return ;
 }

 头文件

 namespace SALES
 {
     const int QUARTERS = ;
     struct Sales{
         double sales[QUARTERS];
         double average;
         double max;
         double min;
     };
     void setsales(Sales &s, const double ar[], int n);
     void setsales(Sales &s);
     void showsales(const Sales&s);
 }

p332.1

 #include<iostream>
 #include<cstdlib>
 #include<cstring>
 using namespace std;

 class Bankacount{
     char name[];
     char num[];
     double deposit;
 public:
     Bankacount(char *pt="nobody", char *ar="", double balance=0.0);
     ~Bankacount();
     void storage(double ct);
     void withdraw(double ct);
     void show()const;
 };

 Bankacount::Bankacount(char *pt, char *ar, double balance)
 {
     strncpy(name, pt, );
     name[] = '\0';
     strncpy(num, ar, );
     num[] = '\0';
     deposit = balance;
 }

 Bankacount::~Bankacount(){

 }

 void Bankacount::storage(double ct){
     if (ct < )
         cout << "the deposit must be positive\n";
     else deposit += ct;
 }

 void Bankacount::withdraw(double ct){
     if (ct<)
         cout << "the deposit must be positive\n";
     else deposit -= ct;
 }

 void Bankacount::show()const{
     cout << "name is " << name << endl
         << "number is " << num << endl
         << "deposit now is " << deposit << endl;
 }

 int main(){
     Bankacount acount1("GE", "asdf", 0.0);
     Bankacount acount2;
     Bankacount acount3 = Bankacount("DELL", "34WE", 2.3);
     acount1.show();
     acount2.show();
     acount3.show();
     acount1.storage(4.5);
     acount2.withdraw(2.7);
     acount1.show();
     acount2.show();

     system("pause");
     return ;
 }