2.21作业

s

#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;
}