C++ Primer 第10章 习题10.25

//10.25.cpp
//定义一个vector容器，存储在未来6个月里要阅读的书的名字
//定义一个set，用于记录已经看过的书名。
//本程序支持从vector中选择一本没有读过而现在要读的书。
//并且支持从已读数目的set中删除书的记录
//在虚拟的6个月后，输出已读和还没有读的书目
#include<iostream>
#include<set>
#include<vector>
#include<string>
#include<cstdlib>
#include<ctime>
using namespace std;

int main()
{
vector<string> books;
set<string> readedbooks;
string name;

//建立保存未来6个月要阅读的书名的vector
cout<<"Enter names for books you'd like to read (Ctrl-z to end):"
<<endl;
while(cin>>name)
books.push_back(name);
cin.clear();	//使流对象重新有效

bool timeOver=false;
string answer, bookName;
//用当前系统时间设置随机数发生种子
srand((unsigned)time(NULL));

//模拟随时间的流逝而改变读书记录
while(!timeOver&& !books.empty())
{
//时间未到6个月且还有书没有度过
cout<<"Would you like to read a book?(Yes/No)"<<endl;
cin>>answer;

if(answer[0]=='y'||answer[0]=='Y')	//在vector中随机选择一本书
{
int i=rand()%books.size();	//产生一个伪随机数
bookName=books[i];
cout<<"You can read this book:"
<<bookName<<endl;
readedbooks.insert(bookName);	//将该书放入已读集合
books.erase(books.begin()+i);	//从vector对象中删除该书

cout<<"Did you read it?(Yes/No)"<<endl;
cin>>answer;
if(answer[0]=='n'||answer[0]=='N')
{
//没有读这本书
readedbooks.erase(bookName);	//从已读集合中删除该书
books.push_back(bookName);
}
}
cout<<"Time over?(Yes/No)"<<endl;
cin>>answer;
if(answer[0]=='y'||answer[0]=='Y')
{
timeOver=true;
}
}
if(timeOver)//虚拟的6个月结束了
{
//输出已读书目
cout<<"books read:"<<endl;
for(set<string>::iterator sit=readedbooks.begin();
sit!=readedbooks.end();++sit)
cout<<*sit<<endl;
//输出还没有读的数目
cout<<"books not read:"<<endl;
for(vector<string>::iterator vit=books.begin();
vit!=books.end();++vit)
cout<<*vit<<endl;
}
else
cout<<"Congratulations! You have read all these books."
<<endl;
return 0;
}