C++命名空间使用代码

namesp.h

#pragma once
#include <string>

namespace pers
{
    using namespace std;
    struct Person
    {
        string fname;
        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 "namesp.h"
#include <iostream>

using namespace std;

void pers::getPerson(Person & rp)
{
    cout << "Enter first name: ";
    cin >> rp.fname;
    cout << "Enter last name: ";
    cin >> rp.lname;
}

void pers::showPerson(const Person & rp)
{
    cout << rp.fname << ", " << rp.lname;
}

void debts::getDebt(Debt & rd)
{
    getPerson(rd.name);
    cout << "Enter debt: ";
    cin >> rd.amount;
}

void debts::showDebt(const Debt & rd)
{
    showPerson(rd.name);
    cout << ": $" << rd.amount << endl;
}

double debts::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()
{
    using debts::Debt;
    using debts::showDebt;

    Debt golf = { {"Benny","Goatsniff"},120.0 };
    showDebt(golf);
    other();
    another();
    
    std::cin.get();
    return 0;
}

void other(void)
{
    using namespace std;
    using namespace debts;

    Person dg = { "Doodles","Glister" };
    showPerson(dg);
    cout << endl;

    Debt zippy[3];
    int i;
    for (int 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;
}