//c_str()就是把string類對象轉(zhuǎn)換成和c兼容的char*類型。
//這是為了與c語言兼容，在c語言中沒有string類型
//故必須通過string類對象的成員函數(shù)c_str()把string 對象轉(zhuǎn)換成c中的字符串樣式
//例如
	string a = "hellofjifj";
	printf("%s\n", a.c_str());
	//printf("%s\n", a);//這樣會有問題

    ofstream OpenFile("file.txt");  
　　if (OpenFile.fail())  
　　{  
　　　　cout<<"打開文件錯誤!"<<endl;  
　　　　exit(0);  
　　}  
    OpenFile << "abc def ghi";//把內(nèi)容寫入file文件  
　　OpenFile.close();    

    const int len=20;  
    char str[len];  
    ifstream OpenFile("file.txt");  
　　if (OpenFile.fail())  
    {  
        cout<<"打開文件錯誤!"<<endl;  
        exit(0);  
    }  
    OpenFile >> str;  
    cout << str << endl;  
    OpenFile.close(); //str的內(nèi)容為abc，而不是abc def ghi(見空格停止)

    const int len=20;  
    char str[len];  
    ifstream OpenFile("file.txt");  
    if (OpenFile.fail())  
    {  
        cout<<"打開文件錯誤!"<<endl;  
        exit(0);  
    }  
    OpenFile.getline(str,20);  
    cout << str << endl;  
    OpenFile.close();//運行結(jié)果：str的內(nèi)容為abc def ghi （一直把一行讀完）

    char ch='1';  
    ofstream OpenFile("file.txt");  
　　if (OpenFile.fail())  
    {  
        cout<<"打開文件錯誤!"<<endl;  
        exit(0);  
    }  
    OpenFile.put(ch); // 把字符1寫入文件
    OpenFile.close();  

    char ch;  
    ifstream OpenFile("file.txt");  
　　if (OpenFile.fail())  
    {  
        cout<<"打開文件錯誤!"<<endl;  
        exit(0);  
    }  
    OpenFile.get(ch);  
    cout << ch; //把字符1從文件中讀到ch（內(nèi)存）中
    OpenFile.close();  

    char ch='a';  
    ofstream OpenFile("file.txt",ios::binary);  
    //以二進制的方式處理，在打開時要用 ios::binary 顯式聲明
　　if (OpenFile.fail())  
    {  
        cout<<"打開文件錯誤!"<<endl;  
        exit(0);  
    }  
    OpenFile.put(ch);  
    OpenFile.close();  

    char ch;  
    ifstream OpenFile("file.txt",ios::binary);  
　　if (OpenFile.fail())  
    {  
        cout<<"打開文件錯誤!"<<endl;  
        exit(0);  
    }  
    OpenFile.get(ch); // 從文件中讀取一個字符
    cout << ch;  
    OpenFile.close(); 

    char ch[12]="12 3 456 78";  
    ofstream OpenFile("file.txt");  
　　if (OpenFile.fail())  
    {  
        cout<<"打開文件錯誤!"<<endl;  
        exit(0);  
    }  
    OpenFile.write(ch, 12);  
    OpenFile.close();  

    char ch[12];  
    ifstream OpenFile("file.txt");  
    if (OpenFile.fail())  
    {  
        cout<<"打開文件錯誤!"<<endl;  
        exit(0);  
    }  
    OpenFile.read(ch,12);  
    cout << ch;  //運行結(jié)果：數(shù)組ch的內(nèi)容為12 3 456 78
    OpenFile.close();  

struct ServerInfo//要讀些的信息類
{
	char _ip[20];
	int  _port;
};
	//C當(dāng)中用法
    //將info中數(shù)據(jù)轉(zhuǎn)成字符串并存入buff中
	ServerInfo info = { "192.0.0.1", 8000 };
	char buff[128];//buff的大小不好確定
	sprintf_s(buff, "%s %d", info._ip, info._port);// 序列化，轉(zhuǎn)成字符串存入buff中
	
    //將buff中數(shù)據(jù)格式化輸出到rinfo中
	ServerInfo rinfo;
	sscanf(buff, "%s%d", rinfo._ip, &rinfo._port);// 反序列化，將字符串buff中數(shù)據(jù)轉(zhuǎn)成規(guī)定格式
	//空格間隔開了

	//C++用法
	//將info中數(shù)據(jù)轉(zhuǎn)成字符串并存到buff中
    ServerInfo info = { "192.0.0.1", 8000 };
	stringstream ssm;//字符串流對象
	ssm << info._ip <<" "<<info._port;//轉(zhuǎn)成字符串
	string buff = ssm.str();//查看字符串
	//從字符串提取至rinfo
	stringstream ssm;
	ssm.str("127.0.0.1 90");//這兩行直接按照下面的寫法也行
	//stringstream ssm("127.0.0.1 90");
	ServerInfo rinfo;
	ssm >> rinfo._ip >> rinfo._port;