C++ Primer Plus 学习笔记第九章最后的一点完结名称空间

素颜马尾好姑娘i 2022-01-29 07:11 181阅读 0赞

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NvdWx3eWI_size_16_color_FFFFFF_t_70][]

![20190521131129406.png][]

示例代码：

namesp.h

#include <iostream>
    namespace pers
    {
      struct Person{
        std::string fname;
        std::string lname;
      };
      void getPerson(Person &);
      void showPerson(const Person &);
    }
    
    namespace debts
    {
      using namespace pers;
      struct Debt
      {
        Person name;
        double amount;
      };
      void getDebt(Debt &);
      void showDebt(const Debt &);
      double sumDebts(const Debt ar[], int n);
    }

namesp.cpp

#include <iostream>
    #include "namesp.h"
    
    namespace pers
    {
      using std::cout;
      using std::cin;
      void getPerson(Person & rp)
      {
        cout << "Enter first name: ";
        cin >> rp.fname;
        cout << "Enter last name: ";
        cin >> rp.lname;
      }
      void showPerson(const Person & rp)
      {
        std::cout << rp.lname << ", " << rp.fname;
      }
    }
    
    namespace debts
    {
      void getDebt(Debt& rd)
      {
        getPerson(rd.name);
        std::cout << "Enter debt: ";
        std::cin >> rd.amount;
      }
      void showDebt(const Debt & rd)
      {
        showPerson(rd.name);
        std::cout << ": $" << rd.amount << std::endl;
      }
      double sumDebts(const Debt ar[], int n)
      {
        double total = 0;
        for (int i =0; i < n; i++)
          total += ar[i].amount;
        return total;
      }
    }

namessp.cpp

#include <iostream>
    #include "namesp.h"
    void other(void);
    void another(void);
    int main(void)
    {
      using debts::Debt;
    
      using debts::showDebt;
      Debt golf = {
       {"Benny", "Goatsniff"}, 120.0};
      showDebt(golf);
      other();
      another();
      return 0;
    }
    
    void other(void)
    {
      using std::cout;
      using std::endl;
      using namespace debts;
      Person dg = {"Doodles", "Glister"};
      showPerson(dg);
      cout << endl;
      Debt zippy[3];
      int i;
      for (i = 0; i < 3; i++)
        getDebt(zippy[i]);
    
      for (i = 0; i < 3; i++)
        showDebt(zippy[i]);
      cout << "Total debt: $" << sumDebts(zippy, 3) << endl;
      return;
    }
    
    void another(void)
    {
      using pers::Person;
      Person collector = {"Milo", "Rightshift"};
      pers::showPerson(collector);
      std::cout << std::endl;
    }

执行结果：

![20190521131255601.png][]

最后 总结：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NvdWx3eWI_size_16_color_FFFFFF_t_70 1][]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NvdWx3eWI_size_16_color_FFFFFF_t_70]: /images/20220129/cd915c9df4ec41d2af469fbcb024c8c7.png
[20190521131129406.png]: /images/20220129/76f34a2572e5420e9db6995c97e5d2c0.png
[20190521131255601.png]: /images/20220129/81262cd7840a43bba2f15e8f2583bc09.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3NvdWx3eWI_size_16_color_FFFFFF_t_70 1]: /images/20220129/a2626e54962f459eb02ba3d39fb94720.png