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#include <iostream>
#include <cstring>using namespace std;class mystring
{private:char*p;int len;public:mystring(const char* p = NULL);~mystring();void copy(const mystring& str);void append(const mystring& str);void show();bool compare(const mystring& str);void swap(mystring& str);void operator=(const mystring& str);mystring operator+(const mystring& str);char& operator[](int i);void operator+=(const mystring& str);
};//默认参数构造函数
mystring::mystring(const char* p):p(NULL),len(0)
{if(p != NULL){this->len = strlen(p);this->p = new char[len+1];strcpy(this->p,p);}
}//析构函数
mystring::~mystring()
{if(p != NULL){delete[] p;}
}//成员方法
/*******************************************************************///拷贝功能
void mystring::copy(const mystring& str)
{if(p != NULL){delete[] p;p = NULL;}len = str.len;if(str.p == NULL){p = NULL;}else{p = new char[len+1];strcpy(p,str.p);}
}//追加功能
void mystring::append(const mystring& str)
{if(str.p == NULL){return;}char* temp = p;len = len + str.len;p = new char[len];strcpy(p,temp);strcat(p,str.p);
}//打印功能
void mystring::show()
{if(p == NULL){return;}cout << p <<endl;
}//比较功能
bool mystring::compare(const mystring& str)
{return strcmp(p,str.p) == 0;
}//交换功能
void mystring::swap(mystring& str)
{char* temp = p;int i = len;p = str.p;str.p = temp;len = str.len;str.len = i;
}//运算符重载
/**********************************************************///重载"="
void mystring::operator=(const mystring& str)
{if(p != NULL){delete[] p;p = NULL;}if(str.p == NULL){p = NULL;len = 0;}else{len = str.len;p = new char[len+1];strcpy(p,str.p);}
}//重载"+"
mystring mystring::operator+(const mystring& str)
{mystring temp;temp.len = len + str.len;temp.p = new char[temp.len];strcpy(temp.p,p);strcat(temp.p,str.p);return temp;
}//重载"+="
void mystring::operator+=(const mystring& str)
{if(str.p == NULL){return;}char* temp = p;len = len + str.len;p = new char[len];strcpy(p,temp);strcat(p,str.p);if(temp != NULL){delete[] temp;}
}//重载"[]"
char& mystring::operator[](int i)
{return p[i];
}int main()
{mystring str("0000");mystring ptr("11111");str = ptr + str; str.show();str[0] = 'A';str.show();str += ptr;str.show();return 0;
}
第二题
#include<iostream>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <cstring>
#include <unistd.h>
#include <pthread.h>using namespace std;struct msg_pack
{long channel;char buf[64];
};class Msg
{private:key_t key;int id;int channel;public:Msg(const char* file);~Msg();void send(const char* buf);string read();Msg& operator[](int num);
};//构造函数定义
Msg::Msg(const char* file)
{if(access(file,F_OK) == -1){cout<<"文件不存在"<<endl;return;}key = ftok(file,1);id = msgget(key,IPC_CREAT|0664);
}//析构函数定义
Msg::~Msg()
{msgctl(id,IPC_RMID,NULL);
}//成员方法：读取数据
string Msg::read()
{msg_pack pack = {0};pack.channel = channel;msgrcv(id,&pack,sizeof(pack.buf),channel,0);return pack.buf;
}//成员方法：发送数据
void Msg::send(const char* buf)
{msg_pack pack = {0};pack.channel = channel;strcpy(pack.buf,buf);msgsnd(id,&pack,strlen(pack.buf),IPC_NOWAIT);
}//重载"[]"运算符，将里面的数据写入消息频道
Msg& Msg::operator[](int num)
{channel = num;return *this;
}
void* pthread_main(void* arg)
{Msg* g = (Msg*)arg;while(1){string s = g[2].read();cout <<"\b\b\b\b\b\b\b"<<"收到的消息为："<< s <<endl;}}int main()
{pthread_t id;Msg m("1.txt");pthread_create(&id,0,pthread_main,&m);char brr[64] = "";while(1){memset(brr,0,sizeof(brr));cout<<"请输入:";cin>>brr;m[1].send(brr);}return 0;
}
第三题
#include <iostream>
#include <sys/sem.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/ipc.h>using namespace std;class Sem
{private:key_t key;int id;int index;public:Sem(const char* file,int x,int y);~Sem();void init(int num);Sem& operator[](int a);friend void operator+(const Sem& m,int i);friend void operator-(const Sem& m,int i);
};//构造函数
Sem::Sem(const char* file,int x,int y)
{if(key = ftok(file,1) == -1){cout <<"没有该文件"<<endl;}id = semget(key,x,IPC_CREAT|0666);for(int i=0; i<x; i++){semctl(id,i,SETVAL,y);}
}//析构函数
Sem::~Sem()
{semctl(id,0,IPC_RMID);
}//手动初始化
void Sem::init(int num)
{semctl(id,index,SETVAL,num);
}//内重载"[]"(写入下标)
Sem& Sem::operator[](int index)
{this->index = index;return *this;
}//外重载"+"(解锁)
void operator+(const Sem& m,int i)
{struct sembuf buf = {0};buf.sem_num = m.index;buf.sem_op = i;buf.sem_flg = SEM_UNDO;semop(m.id,&buf,1);
}//外重载"-"(解锁)
void operator-(const Sem& m,int i)
{struct sembuf buf = {0};buf.sem_num = m.index;buf.sem_op = (0-i);buf.sem_flg = SEM_UNDO;semop(m.id,&buf,1);
}int main()
{Sem s("2.txt",2,0);s[1].init(1);pid_t pid = fork();if(pid>0){while(1){s[1] - 1;cout << "父进程" <<endl;sleep(1);s[0] + 1;}}if(pid == 0){while(1){s[0] - 1;cout << "子进程" <<endl;sleep(1);s[1] + 1;}}return 0;
}