C++ Primer Plus 第六版第八章编程练习答案

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我是靠谱客的博主高大大船，最近开发中收集的这篇文章主要介绍C++ Primer Plus 第六版第八章编程练习答案，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

#include <iostream>
#include <cstring>
#include <cctype>

using namespace std;

void q1();
void print(char * a, int b = 0);

const int Len = 40;
struct CandyBar
{
   char maker[Len];
   double weight;
   int calo;
};
void q2();
void setnum(CandyBar & a, char * m = "Millennium Munch", double w = 2.85, int c = 350);
void show(const CandyBar & a);

void q3();
void Upper(string & a);

struct stringy{
char * str;
int ct;
};
void q4();
void set(stringy & a, char * b);
void show(const stringy & a, int i = 1);
void show(const char a[], int i = 1);

void q5();
template<typename T>
T max5(const T a[]);

void q6();
template<typename T>
T maxn(const T a[], int n);

typedef char * charptr;
/*
若写为　
template<>
char * maxn(const char * a[], int n);
会报错：template-id 'maxn<>' for 'char* maxn(const char**, int' does not match　any template declaration

在模板的定义中， const T 所代表的是一个常量。那么 const char* 是一个常量吗？
不是，它是一个非常量指针（编译器允许改变它的值，让它指向别处），指向一个常量（编译器不允许修改它所指向的内容）。
所以，编译器判定显式特化与函数模板定义不匹配。

正确的写法是:

typedef char* char_ptr;

template<> char_ptr max_e (const char_ptr ar[], int n)

或者写为

template<> char* max_e(char* const arr[],int len)

注意只有char* const 才能对应原来的模板中的const T

而不是const char* 对应 const T !

*/
template<>
charptr maxn(const charptr a[], int n);

void q7();
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()
{
q7();
return 0;
}

void q1()
{
   char a[50] = "Hello";
   cout << "print(a):" << endl;
   print(a);
   cout << "print(a,2):" << endl;
   print(a, 2);
}

void print(char * a, int b)
{
   if (b)
   {
       while(b--)
       print(a, b);
   }
   else
   cout << a << endl;
}

void q2()
{
   CandyBar num1, num2;
   setnum(num1, "xy", 1.2, 230);
   setnum(num2);
   show(num1);
   show(num2);
}

void setnum(CandyBar & a, char * m, double w, int c)
{
   int i = 0;
   for (; strlen(m) < (Len - 1) && i < strlen(m); i++)
       a.maker[i] = m[i];
   a.maker[i] = '';
   a.weight = w;
   a.calo = c;
}

void show(const CandyBar & a)
{
   cout << "CandyBar maker: " << a.maker << endl;
   cout << " weight: " << a.weight << endl;
   cout << " calo: " << a.calo << endl;
}

void q3()
{
   cout << "Enter a string (q to quit): " ;
   string a;
   getline(cin, a);
   while (a != "q")
   {
       Upper(a);
       cout << a << endl;
       cout << "Enter a string (q to quit): ";
       getline(cin, a);
   }
   cout << "Bye." << endl;
}

void Upper(string & a)
{
   for (int i = 0; i < a.length(); i++)
   {
       if(!isupper(a[i]))
       a[i] = toupper(a[i]);
   }
}

void q4()
{
   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);
   show("Done!");
   delete [] beany.str;
}

void set(stringy & a, char * b)
{
   a.ct = strlen(b);
   a.str = new char[a.ct+1];
   strcpy(a.str, b);
}

void show(const stringy & a, int i)
{
for (int j = 0; j < i; j++)
cout << a.str << endl;
}

void show(const char a[], int i)
{
for (int j = 0; j < i; j++)
cout << a << endl;
}

void q5()
{
   int a[5] = {1, 3, 5, 2, 4};
   double b[5] = {1.3, 3.2, 2, 4.3, 2.1};
   cout << max5(a) << endl;
   cout << max5(b) << endl;
}

template<typename T>
T max5(const T a[])
{
   T c = a[0];
   for (int i = 0; i < 5; i++)
   {
       if(c < a[i])
       c = a[i];
   }
   return c;
}

void q6()
{
   int a[6] = {1, 2, 5, 7, 2, 1};
   double b[4] = {1.2, 4.3, 2.1, 5.3};
   cout << maxn(a, 6) << endl;
   cout << maxn(b, 4) << endl;
   const charptr c[5] =
   {
       "hello",
       "world",
       "name",
       "bye",
       "puppy"
   };
   cout << maxn(c, 5) << endl;
}

template<typename T> T maxn(const T *a, int n)
{
   T c = a[0];
   for (int i = 0; i < n; i++)
   {
       if (c < a[i])
       c = a[i];
   }
   return c;
}

template<> charptr maxn(const charptr a[], int n)
{
   int len = strlen(a[0]);
   charptr pd = &a[0][0];
   for (int i = 0; i < n; i++)
   {
       if (strlen(a[i]) > len)
       {
           pd = &a[i][0];
       len = strlen(a[i]);
       }
   }
   return pd;
}

void q7()
{
   int things[6] = {13, 31, 103, 301, 310, 130};
   struct 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 << "The sum of things:" << SumArray(things, 6) << endl;
   cout << "The sum of debts: " << SumArray(pd, 3) << endl;
}

template <typename T>
T SumArray(T arr[], int n)
{
   T sum = 0;
   for (int i = 0; i < n; i++)
   sum += arr[i];
   return sum;
}

template <typename T>
T SumArray(T * arr[], int n)
{
   T sum = 0;
   for (int i = 0; i < n; i++)
   sum += *arr[i];
   return sum;
}