/*** 第二章：对象的创建和使用 ***/
#include<iostream>
#include<string>
#include<fstream>
#include<vector>
using namespace std;
int main()
{
    // output  13 in the way of octal & hex;
    cout << "the octal form is :"
         << oct << 13 << endl;         
    cout << "the hex form is   :"
         << hex << 13 << endl;  
    // the system can recognize floating-point automatically;     
    cout << "the float number is:"
         << 3.14159 << endl;
    // chang ASCII code 27 to symbol "escape";
    cout << "the non-printing character:"
         << char(27) << endl;
    // usage of object cin;
    int number;
    cout << "enter one integer:" << endl;
    cin  >> number;          
    cout << "number is:" << dec << number << endl;
    // connect the strings with using the "string" class
    cout << "Display connenting the strings: " << endl;
    string s1,s2;       //empty strings;
    string s3 = "hello,my ";//initializing;
    string s4("name is");   //initializing;
    s1 = "Oh!~";
    s2 = s3 + s4 + " ";     //connect...
    s1 += s2;               //appending to s1...
    cout << s1 + "mumu" << endl;
    // copy one file to another with one line at a time;
    // we need class <fstream>
    ifstream in("chapter2.cpp");// object ifstream opened for reading only;
    ofstream out("Cpchapter2.cpp");//object ofstream  for writing only;
    string temp;
    while(getline(in,temp))   //getline() will discard the "\n";
         out << temp << "\n";
    // copy an entire file into a single string
    // object string is dynamic & don't worry about the memory allocation;
    string str1,str2;
    while(getline(in,str2))
         str1 += str2 +"\n";
    cout << str1;
    // introduction to standard container class -- Vector
    // vector class is a template , you can use it in different classes effectively
    ifstream in1("chapter2.cpp");
    string temp1;
    vector<string> v;//make a vector which only loads string objects;
    while(getline(in1,temp1))
         v.push_back(temp1); // member function adds line to the end of container ;
    for(int i=0;i<v.size(); ++i)
       cout << i <<":" <<v[i] << endl;
    system("pause");
}
/*** 练习感悟 ***/
//向容器中输入元素的正确方式是：
                                float temp;
                                cin >> temp;
                                v.push_back(temp);
              //    错误方式是：
                                cin >> v[i];
              // v[i]的使用只用在输出和对元素进行操作(赋值)的时候正确。
//读入回车键的正确方法：
//习题：将一个文件的内容逐行输出，要求当用户按下回车键的时候输出下一行。
#include<iostream>
#include<fstream>
#include<string>
using namespace std;
int main()
{
    ifstream  in("chapter2.cpp");
    string temp;
    char ch;
    while(getline(in ,temp))
    {
         cout << temp;
         ch = getchar();
         if(ch != '\n')
            break;
    }
    system("pause");
}
//错误方法：cin >> ch; 系统无法识别输入的是'\r' OR '\n'...