#include<iostream>

using namespace std;

const int Size=;

void strcount(const char *str){//const表示str指针不能修改指向的内容（不过可以指向另外一块内容）

    static int total=;//static静态变量，首次初始化后，其值一直存在（即第二次调用strcount函数时，total的值不会再次初始化）

    int count=;

    cout<<"\""<<str<<"\" contains ";

    while (*str++)//先判断*str是否为NULL，然后再str++

        count++;

    total+=count;

    cout<<count<<" characters\n";

    cout<<total<<" characters total!\n";

}

void main() {

    char in[Size];

    char next;

    cout<<"Enter a line:"<<endl;

    cin.get(in,Size);//最多接收Size-1个字符+1个'\0'

    while (cin)    // ==while(!cin.fail()),即读入流成功

    {

        cin.get(next);

        while(next!='\n')    //若next不是换行符

            cin.get(next);

        strcount(in);

        cout<<"Enter next line (empty line to quit):\n";

        cin.get(in,Size);

    }

    cout<<"Bye!"<<endl;

    system("pause");

}

 #include<iostream>

 #include<new>    //定位new运算符

 using namespace std;

 const int BUF=;

 const int N=;

 char buff[BUF];

 void main() {

     double *p1,*p2;

     int i;

     cout<<"Calling"<<endl;

     p1=new double[N];//常规new：p1是double指针

     p2=new (buff) double[N];//定位new运算符：将数组p2放在了数组buff中

     for (i = ; i < N; i++)

         p2[i]=p1[i]=+20.0*i;

     cout<<"Memory addresses:"<<endl<<" heap: "<<p1<<" static: "<<(void *)buff<<endl;//buffer是char指针，所以要使用(void *)对buffer进行强转，否则将显示字符串

     cout<<"Memory contents:"<<endl;

     for (i = ; i < N; i++)

     {

         cout<<p1[i]<<" at "<<&p1[i]<<";";

         cout<<p2[i]<<" at "<<&p2[i]<<endl;

     }

     cout<<"\nCalling new"<<endl;

     double *p3,*p4;

     p3=new double[N];

     p4=new (buff) double[N];

     for (i = ; i < N; i++)

         p4[i]=p3[i]=+40.0*i;

     cout<<"Memory contents:"<<endl;

     for (i = ; i < N; i++)

     {

         cout<<p3[i]<<" at "<<&p3[i]<<";";

         cout<<p4[i]<<" at "<<&p4[i]<<endl;

     }

     cout<<"\nCalling new third"<<endl;

     delete [] p1;

     p1=new double [N];

     p2=new (buff+N*sizeof(double)) double[N];

     for (i = ; i < N; i++)

         p2[i]=p1[i]=+60.0*i;

     cout<<"Memory contents:"<<endl;

     for (i = ; i < N; i++)

     {

         cout<<p1[i]<<" at "<<&p1[i]<<";";

         cout<<p2[i]<<" at "<<&p2[i]<<endl;

     }

     //buff指定的内存是静态内存，所以不能delete

     delete [] p1;

     delete [] p3;

     system("pause");

 }

#include<string>

namespace pers{        //包含Person结构的定义和两个函数原型

    struct Person{

        std::string fname;

        std::string lname;

    };

    void getPerson(Person &);//引用

    void showPerson(const Person &);

}

namespace debts{    //定义Debt结构，用于存储人名和金额，使用using编译指令，让pers中的名称在debts空间也能使用

    using namespace pers;

    struct Debt{

        Person name;

        double amount;

    };

    void getDebt(Debt &);

    void showDebt(const Debt &);

    double sumDebts(const Debt ar[],int n);

}

#include<iostream>

#include<string>

#include "namesp.h"//自己编写的头文件只能使用引号"",系统自带的头文件使用<>,不过""也能用

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){

        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=;

        for (int i = ; i < n; i++)

            total+=ar[i].amount;

        return total;

    }

}

#include<iostream>

#include "namesp.h"

using std::cout;

using std::endl;

void other(){

    using namespace debts;

    Person dg={"Doodles","Glister"};

    showPerson(dg);

    cout<<endl;//因为showPerson没有换行

    Debt zippy[];

    int i;

    for (i = ; i < ; i++)

        getDebt(zippy[i]);

    for (i = ; i < ; i++)

        showDebt(zippy[i]);

    cout<<"Total debt: $"<<sumDebts(zippy,)<<endl;

}

void another(){

    using pers::Person;

    Person collector={"Milo","Rightshift"};

    pers::showPerson(collector);

    cout<<endl;

}

void main(){

    using debts::Debt;

    using debts::showDebt;

    Debt golf={{"Benny","Goatsniff"},120.0};

    showDebt(golf);

    other();

    another();

    system("pause");

}