第八章4-7题

第四题

#include<iostream>
#include<cstring>
using namespace std;
struct stringy
{
  char* str;
  int Len;
};
void set(stringy& st , const char* body);
void showInfo(const stringy& st , int times = 1);  //默认输出1次
void showInfo(const char* ch , int times = 1);
int main()
{
  stringy beany;
  char testing[] = "Reality isn't what it used ti be.";
  set(beany,testing);
  showInfo(beany);
  showInfo(beany,2);
  testing[0] = 'D';
  testing[1] = 'u';
  showInfo(testing);
  showInfo(testing,3);
  showInfo("Done!");
  delete [] beany.str;   //set()函数动态分配的内存
  return 0;
}
void set(stringy& st , const char* body)
{
  int lenght = strlen(body);
  st.Len = lenght;
  st.str = new char[lenght+1];
  strcpy(st.str,body);
}
void showInfo(const stringy& st , int times)
{
  cout<<"输出"<<times<<"次"<<endl;
  for(int i = 0 ; i < times ; ++i)
   {
    cout<<"结构字符:"<<st.str<<endl;
    cout<<"结构字符长度:"<<st.Len<<endl;
   }
}
void showInfo(const char* ch , int times)
{
  cout<<"输出"<<times<<"次"<<endl;
  for(int i = 0 ; i < times ; ++i)
   cout<<ch<<endl;
}   
    

第五题

#include<iostream>
const int Len = 5;
template<typename T>
T maxArray(const T* arr);

int main()
{
  using namespace std;
  int Ints[Len] = {1,2,3,5,4};
  double Doubles[Len] = {1.1,4.3,6.5,3.4,1.1};
  cout<<"最大的int为"<<maxArray(Ints)<<endl;
  cout<<"最大的double为"<<maxArray(Doubles)<<endl;
 return 0;
}
template<typename T>
T maxArray(const T* arr)
{
  T maxEle = *arr;
  for(int i = 0 ; i < Len ; ++i)
   {
    if(maxEle < *(arr+i))
     maxEle = *(arr+i);
   }
  return maxEle;
}

第六题

#include<iostream>
#include<cstring>
using namespace std;
template<typename T>
const T maxn(const T* arr , int lenght);
template<> const char* maxn(const char** names , int lenght);  //char*具体化

int main()
{
  int Ints[6] = {1,2,3,4,5,6};
  double Doubles[4] = {1.1,2.2,3.4,5.0};
  int maxInt = maxn(Ints,6);
  double maxDouble = maxn(Doubles,4);
  cout<<"最大的int值为"<<maxInt<<endl;
  cout<<"最大的double值为"<<maxDouble<<endl;
 
  const char* names[5] = {"a","b","ccc","e","f"};
  const char* maxName = maxn(names,5);
  cout<<"最长的char值为"<<maxName<<endl;
 return 0;
}
  
template<typename T>
T maxn(const T* arr , int lenght)
{
  T max_arr = *arr;
  for(int i = 0 ; i < lenght ; ++i)
  {
   if(max_arr < *(arr+i))
    max_arr = *(arr+i);
  }
  return max_arr;
} 
  
template<> const char* maxn(const char** names , int lenght)
{
  int maxLen = strlen(names[0]);
  int maxEle = 0;
  for(int i = 0 ; i < lenght ; ++i)
   {
     if(maxLen < strlen(*(names+i)))
      {
       int mid = strlen(*(names+i)); 
       cout<<mid<<endl;
       maxLen = strlen(*(names+i));
       maxEle = i;
      }
   }
  return *(names + maxEle);
}

第七题

#include<iostream>
template<typename T>
T sumArray(const T arr[] , int lenght);   //模板A
template<typename T>
T sumArray(const T* arr[] , int lenght);   //模板B
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);
  int sumOfThings = sumArray(things,6);  //调用模板A
  double sumOfpd = sumArray(pd,3);  //调用模板B
  cout<<"things总和为"<<sumOfThings<<endl;
  cout<<"pd总和为"<<sumOfpd<<endl;
 return 0;
}

template<typename T>
T sumArray(const T arr[] , int lenght)
{
  T sum = arr[0];
  for(int i = 1 ; i < lenght ; ++i)
   sum += arr[i];
  return sum;
}
template<typename T>
T sumArray(const T* arr[] , int lenght)
{
  T sum = *(arr[0]);
  for(int i = 1 ; i < lenght ; ++i)
   sum += *(arr[i]);
  return sum;
}