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编写如下类: class File{ FILE* fp }; 1:构造函数，打开一个指定的文件 2:write函数 向文件中写入数据 3：read函数，从文件中读取数据，以string类型返回

代码实现：

#include <iostream>using namespace std;class myfile{FILE *fp;
public:myfile(const char *path,const char *type);//通过fp绑定一个构造函数~myfile();//通过fp绑定一个析构函数int write(char *buf,int signal_size,int terms);//申明一个write函数，向文件中写入数据int read(char *buf,int signal_size,int terms);//申请一个read函数，从文件中读取数据，返回string类型
};
myfile::myfile(const char *path,const char *type){fp=fopen(path,type);if(fp==NULL){perror("fopen");}
}
myfile::~myfile(){fclose(fp);
}
int myfile::write(char *buf,int signal_size,int terms){int res=fwrite((char *)buf,signal_size,terms,fp);return res;
}
int myfile::read(char *buf,int signal_size, int terms){int res=fread((char *)buf,signal_size,terms,fp);return res;
}
int main()
{myfile file_src={"C:\\Users\\pzctj\\Documents\\81_C++\\day2\\myfile\\main.cpp","r"};myfile file_dest={"myfile.txt","w"};char str[1024]={0};// string buf=str;while(1){//buf.clear();int res=file_src.read((char *)str,1,1024);if(res==0){cout << "文件读取结束" << endl;break;}file_dest.write((char *)str,1,res);}return 0;
}

单例模式实现：

懒汉模式： 

#include <iostream>using namespace std;class signalTon{
private:class Mutex{pthread_mutex_t mutex;public:Mutex(){pthread_mutex_init(&mutex,NULL);cout << "无参互斥锁构造函数" << endl;}void lock(){pthread_mutex_lock(&mutex);}void unlock(){pthread_mutex_unlock(&mutex);}};signalTon(){cout << "无参signalTon构造函数" << endl;}static Mutex mutex;
public:signalTon(const signalTon& r)=delete ;//删除自动分配的拷贝构造函数//signalTon()=default;//确保必须分配构造函数//公开接口，用来调用构造函数，构建唯一对象或者返回唯一对象static signalTon* getInstance(){mutex.lock();static signalTon* instance=NULL;if(instance==NULL){sleep(1);//延时1秒，对于多线程懒汉模式可能if判断就不起作用，因此引入互斥锁instance=new signalTon;//堆区开辟空间并调用构造函数为对象初始化}mutex.unlock();return instance;}
};
signalTon::Mutex signalTon::mutex;//静态成员属性mutex开辟空间
void* task(void *arg){signalTon* s1=signalTon::getInstance();cout << s1 << endl;
}int main()
{pthread_t tid;pthread_create(&tid,NULL,task,NULL);pthread_detach(tid);signalTon* s1=signalTon::getInstance();cout << s1 << endl;return 0;
}

饿汉模式： 

#include <iostream>using namespace std;class signalTon{
private:signalTon(){cout << "无参signalTon构造函数" << endl;}static signalTon* instance;
public:signalTon(const signalTon& r)=delete ;//删除自动分配的拷贝构造函数//signalTon()=default;//确保必须分配构造函数//公开接口，用来调用构造函数，构建唯一对象或者返回唯一对象static signalTon* getInstance(){return instance;}
};
signalTon* signalTon::instance=new signalTon;
void* task(void *arg){signalTon* s1=signalTon::getInstance();cout << s1 << endl;
}int main()
{pthread_t tid;pthread_create(&tid,NULL,task,NULL);pthread_detach(tid);signalTon* s1=signalTon::getInstance();cout << s1 << endl;return 0;
}