筆記較為零散，都是自己不熟悉的知識點。
習題答案至於一個.cc中，需要執行某一題直接修改#define NUM**， 如執行第一題為#define NUM11，題1.24定義為NUM124
chapter 1

1、std::cout << "Entertwo numbers:" << std::endl;等價於

std::cout<< "Enter two numbers:";

std::cout << std::endl;

2、名稱空間的作用是防止與庫中定義的名字發生衝突，其副作用是，當使用標準庫中的名字時必須顯示地表達出使用的是名稱空間std下的名字。

3、for (int val = 1; val <= 10; ++val)

對於for迴圈內的val變數，當結束迴圈後不再可訪問

4、檔案結束符

ctrl+d for unix/linux/ etc 
ctrl+z for windows/dos

一旦測試失敗，while 終止並退出迴圈體，執行 while 之後的語句。該語

句在輸出 sum 後輸出 endl，endl 輸出換行並重新整理與 cout 相關聯的緩衝區。

最後，執行 return，通常返回零表示程式成功執行完畢。

http://www.cnblogs.com/tangdoudou/p/3385149.html

exit或return，只能使用0~255之間的值，-1的unsigned值就是255.

#include<iostream>
#include "Sales_item.h"
#define NUM120
//
using namespace std;


int answerEample(int value1,int value2);


int main(){
/*1.1*/
#ifdef NUM11
        cout<<"C++程式一般涉及兩類檔案：標頭檔案和原始檔。檔案字尾通常表明檔案的型別,"
                                "如標頭檔案字尾可以是.h或.hpp;原始檔的字尾可以是.cc或.cpp，具體的字尾與使用的編譯器有關"<<endl;
#endif
/*1.2*/
#ifdef NUM12
        cout<<"window和linux系統下不會報告main函式的執行失敗，所以程式返回-1或返回1在執行效果上並沒有什麼不同,"
                        "但是,DOS命令下執行程式，然後鍵入echo %ERRORLEVEL%,則會顯示返回值-1，linux系統下，鍵入echo $? 則會返回255"<<endl;
#endif 
/*1.3*/
#ifdef NUM13
        cout<<"Hello world"<<endl;
#endif 
/*1.4*/
#ifdef NUM14
        cout<<"Enter two number: "<<endl;
        int v1, v2;
        cin >> v1 >> v2;
        cout<< "The product of " <<v1<<" and "<<v2<<" is "<<v1*v2<<endl;
#endif 
/*1.5*/
#ifdef NUM15
        cout<<"Enter two number: "<<endl;
        int v1, v2;
        cin >> v1 >> v2;
        cout<< "The product of ";
        cout<<v1;
        cout<<" and ";
        cout<<v2;
        cout<<" is ";
        cout<<v1*v2;
        cout<<endl;
#endif 
/*1.6*/
#ifdef NUM16
        cout<<"程式碼不合法"
                "第1,2,3行的末尾有分號，表示這段程式碼分別構成三條語句."
                "'<<'是二元操作符，在第2,3兩行中,第一個'<<'缺少左運算元，因此不合法。應該在2,3行開頭加上cout. "<<endl;
#endif
/*1.7*/
#ifdef NUM17
/*
 * commet pairs /(兩個**) /cannot nest
 * "cannot nest" is considered source code.
 * as is the rest of the problem 
*/
        cout<<"錯誤資訊：註釋不可巢狀。"<<endl;
#endif
/*1.8*/
#ifdef NUM18
        cout<< "第1,2,4行合法。"
                "第3行<<操作符之後到第二個雙引號之前的部分被註釋掉了，導致<<操作符的右運算元不是一個完整的字串."<<endl;
#endif
/*1.9*/
#ifdef NUM19
        int sum(0), val(50);
        while(val <= 100){
                sum += val;
                ++val;
        }
        cout<<" Sum of 50 to 100 is: "<<sum<<endl;
#endif
/*1.10*/
#ifdef NUM110
        int i(10);
        while(i >= 0){
                cout<< i << " ";
                --i;
        }
        cout<<endl;
#endif
/*1.11*/
#ifdef NUM111
        int v1,v2,low,high;
        cout<< "Enter two numbers: "<<endl;
        cin >> v1 >> v2;
        while(v1 <= v2){
                cout<< v1 <<" ";
                ++v1;
        }
#endif
/*1.12*/
#ifdef NUM112
        int sum = 0;
        for(int i = -100; i<=100; ++i)
                sum += i;
        cout<<"-100 到 100 整數相加: "<<sum<<endl;
#endif
/*1.13*/
#ifdef NUM113
        int sum(0), val(50);
        for(val=50; val <= 100; ++val)
                sum += val;
                cout<< "The sum of numbers from 50 to 100: "<<sum <<endl;


        int i(10);
        for(i=10; i>=0; --i)
                cout<< i <<" ";
        cout<<endl;


        int v1,v2,low,high;
        cout<< "Enter two numbers: "<<endl;
        cin >> v1 >> v2;
        if(v1 <= v2){
                low  = v1;
                high = v2;
        }else{
                low = v2;
                high = v1;
        }
        for(;v1 <= v2; ++v1)
                cout<<v1 <<" ";
        cout<<endl;
#endif
/*1.14*/
#ifdef NUM114
        cout<<" for迴圈,迴圈控制變數的初始化和修改都放在語句頭部分，形式簡潔，特別適用於迴圈次數已知的情況，"
                " while迴圈,迴圈控制變數的初始化一般放在while迴圈的之前，迴圈控制變數的修改一般放在迴圈體中，"
                "形式不如for簡潔，但是比較適用於迴圈次數不易預知的情況下。"<<endl;
#endif
/*1.16*/
#ifdef NUM116
        int sum(0), val;
        while(cin >> val)
                sum += val;
        cout<< "The sum is: "<<sum <<endl;
#endif
/*1.17*/
#ifdef NUM117
        cout<<"下載我上傳資源中的第五版原始碼測試。"<<endl;
#endif
/*1.19*/
#ifdef NUM119
        int v1,v2,low,high;
        cout<< "Enter two numbers: "<<endl;
        cin >> v1 >> v2;
        if(v1 <= v2){
                low  = v1;
                high = v2;
        }else{
                low = v2;
                high = v1;
        }
        while(v1 <= v2){
                cout<< v1 <<" ";
                ++v1;
        }
#endif
/*1.20*/
#ifdef NUM120
        Sales_item book;
        cout<<"Enter transactions: "<<endl;
        while(cin>> book){
                cout << "ISBN, number of copies sold, "
                        " total revenue, and average price are: "<<endl;
                cout<< book <<endl;
        }
#endif
/*1.21*/
#ifdef NUM121
        Sales_item book1, book2;
        cin >> book1 >> book2;
        if(book1.same_isbn(book2))
                cout<<book1 + book2 <<endl;
        else
                cout<<"The two books have different ISBN "<<endl;
#endif
/*1.22*/
#ifdef NUM122
        Sales_item total, book;
        cout<<" Enter transactions: "<<endl;
        if(cin>>total){
                while(cin >> book){
                        if(total.same_isbn(book))
                                total = total + book;
                        else
                                cout<<"differ ISNB "<<endl;
                        return -1;
                }
                cout << "ISBN, number of copies sold, "
                        " total revenue, and average price are: "<<endl;
                cout<<total<<endl;
        }else
                cout<<"Input error " <<endl;
                return -255;
#endif
/*1.23 */
#ifdef NUM123
        Sales_item book1,book2;
        int count(0);
        cout<<"Enter transctions: "<<endl;
        cin >> book1;
        count = 1;
        while(cin >> book2)
                if(book1.same_isbn(book2))
                        ++count;
                else {
                        cout<<"Transaction amount of previous ISBN: "<<endl;
                        book1 = book2;
                        count = 1;
                }
        cout << "Transction amount of the last ISBN "<< count  <<endl;
#endif