练习10.29：编写程序，使用流迭代器读取一个文本文件，存入一个vector中的string里。

练习10.30：使用流迭代器，sort和copy从标准输入读取一个整数序列，将其排序，并将结果写到标准输出。

练习10.31：修改前一题的程序，使其之打印不重复的元素。你的程序应使用unique_copy（参见10.4.1节，第359页）。

练习10.32：重写1.6节（第21页）中的书店程序，使用一个vector保存交易记录，使用不同算法完成处理。使用sort和10.3.1节（第345页）中的compareIsbn函数来排序交易记录，然后使用find和accumulate求和。

练习10.33：编写程序，接受三个参数：一个输入文件和两个输出文件的文件名。输入文件保存的应该是整数。使用istream_iterator读取输入文件。使用ostream_iterator将奇数写入第一个输出文件，每个值之后都跟一个空格。将偶数写入第二个输出文件，每个值都独占一行。

答：见练习10.29.cpp-练习10.33.cpp

练习10.29

/*
*练习10.29 
*2015/9/8 
*问题描述：练习10.29：编写程序，使用流迭代器读取一个文本文件，存入一个vector中的string里。
*说明：istream_iterator的使用,注意要使用istream_iterator，要包含 iterator头文件 
*作者：Nick Feng
*邮箱：[email protected] 
*/

#include <iostream>
#include <string>
#include <algorithm>
#include <vector>
#include <fstream>
#include <iterator> 
using namespace std;

int main()
{
    vector<string> vec;
    string s;
    ifstream in("afile.txt");
    istream_iterator<string> str_it(in),eof; 
    while(str_it != eof)
        vec.push_back(*str_it++);

    for(int i = 0; i != vec.size(); ++i)
        cout << vec[i] << " ";
        cout << endl;   
    return 0;
} 

练习10.30

/*
*练习10.30 
*2015/9/8 
*问题描述：练习10.30：使用流迭代器，sort和copy从标准输入读取一个整数序列，将其排序，并将结果写到标准输出。
*说明：istream_iterator的使用,注意要使用istream_iterator，要包含 iterator头文件 
*作者：Nick Feng
*邮箱：[email protected] 
*/

#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
using namespace std;

int main()
{
    vector<int> vec;
    istream_iterator<int> int_it(cin), eof;
    while(int_it != eof)
        vec.push_back(*int_it++);
    sort(vec.begin(),vec.end()); //如果写成vec.cbegin(),vec.cend()报错，因为vec排序后被改变了 
    ostream_iterator<int> out_iter(cout, " ");
    copy(vec.cbegin(),vec.cend(),out_iter);
    cout << endl;
    return 0;
}

练习10.31

/*
*练习10.31 
*2015/9/8 
*问题描述：修改前一题的程序，使其之打印不重复的元素。你的程序应使用unique_copy（参见10.4.1节，第359页）。
*说明：要包含 iterator头文件 
*作者：Nick Feng
*邮箱：[email protected] 
*/

#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>

using namespace std;

int main()
{

    istream_iterator<int> int_it(cin), eof;
    ostream_iterator<int> out_iter(cout," ");
    vector<int> vec(int_it,eof);
    sort(vec.begin(),vec.end());
    unique_copy(vec.begin(), vec.end(), out_iter);
    cout << endl;
    return 0;   
} 

练习10.32

/*
*练习10.32 
*2015/9/9 
*问题描述：练习10.32：重写1.6节（第21页）中的书店程序，使用一个vector保存交易记录，使用不同算法完成处理。使用sort和10.3.1节（第345页）中的compareIsbn函数来排序交易记录，然后使用find和accumulate求和。 
*说明：这道题并不是想象中那么容易
*作者：Nick Feng
*邮箱：[email protected] 
*/
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <iterator>
#include "Sales_item.h"

using namespace std;

bool compareISBN(const Sales_item &lhs, const Sales_item &rhs)
{
    return lhs.isbn() < rhs.isbn();
}


int main()
{   
    ifstream in("Sales_data.txt");
    istream_iterator<Sales_item> sale_in(in),eof;
    ostream_iterator<Sales_item> out_iter(cout, "\n");
    vector<Sales_item> vec(sale_in,eof);               
    //复制文本输入的内容，保存到vector 
    copy(vec.begin(),vec.end(), out_iter);             
    //这里打印的是没有排序的，即是文本中的内容 
    cout << endl;

    sort(vec.begin(),vec.end(),compareISBN);  //进行排序 
    copy(vec.begin(),vec.end(), out_iter);    //这里打印的是排序之后的内容 
    cout << endl;

    auto wc =  find_if(vec.begin(),vec.end(),[](const Sales_item &rhs){ return rhs.isbn() == "Jack";}); 
    //这一步很很重要，途中，会详细说明 
    copy(vec.begin(),wc,out_iter);                             
    //这里只打印ISBN号为Hero的信息 
    cout << accumulate(vec.begin(),wc,Sales_item("Hero"));    
    //计算ISBN号为“Hero”的结果 
    cout << endl; 

    return 0;   
} 

Sales_item.h

/*
 * This file contains code from "C++ Primer, Fifth Edition", by Stanley B.
 * Lippman, Josee Lajoie, and Barbara E. Moo, and is covered under the
 * copyright and warranty notices given in that book:
 * 
 * "Copyright (c) 2013 by Objectwrite, Inc., Josee Lajoie, and Barbara E. Moo."
 * 
 * 
 * "The authors and publisher have taken care in the preparation of this book,
 * but make no expressed or implied warranty of any kind and assume no
 * responsibility for errors or omissions. No liability is assumed for
 * incidental or consequential damages in connection with or arising out of the
 * use of the information or programs contained herein."
 * 
 * Permission is granted for this code to be used for educational purposes in
 * association with the book, given proper citation if and when posted or
 * reproduced.Any commercial use of this code requires the explicit written
 * permission of the publisher, Addison-Wesley Professional, a division of
 * Pearson Education, Inc. Send your request for permission, stating clearly
 * what code you would like to use, and in what specific way, to the following
 * address: 
 * 
 *     Pearson Education, Inc.
 *     Rights and Permissions Department
 *     One Lake Street
 *     Upper Saddle River, NJ  07458
 *     Fax: (201) 236-3290
*/ 

/* This file defines the Sales_item class used in chapter 1.
 * The code used in this file will be explained in
 * Chapter 7 (Classes) and Chapter 14 (Overloaded Operators)
 * Readers shouldn't try to understand the code in this file
 * until they have read those chapters.
*/

#ifndef SALESITEM_H
// we're here only if SALESITEM_H has not yet been defined 
#define SALESITEM_H

// Definition of Sales_item class and related functions goes here
#include <iostream>
#include <string>

class Sales_item {
// these declarations are explained section 7.2.1, p. 270 
// and in chapter 14, pages 557, 558, 561
friend std::istream& operator>>(std::istream&, Sales_item&);
friend std::ostream& operator<<(std::ostream&, const Sales_item&);
friend bool operator<(const Sales_item&, const Sales_item&);
friend bool 
operator==(const Sales_item&, const Sales_item&);
public:
    // constructors are explained in section 7.1.4, pages 262 - 265
    // default constructor needed to initialize members of built-in type
    Sales_item(): units_sold(0), revenue(0.0) { }
    Sales_item(const std::string &book): 
                  bookNo(book), units_sold(0), revenue(0.0) { }
    Sales_item(std::istream &is) { is >> *this; }
public:
    // operations on Sales_item objects
    // member binary operator: left-hand operand bound to implicit this pointer
    Sales_item& operator+=(const Sales_item&);

    // operations on Sales_item objects
    std::string isbn() const { return bookNo; }
    double avg_price() const;
// private members as before
private:
    std::string bookNo;      // implicitly initialized to the empty string
    unsigned units_sold;
    double revenue;
};

// used in chapter 10
inline
bool compareIsbn(const Sales_item &lhs, const Sales_item &rhs) 
{ return lhs.isbn() == rhs.isbn(); }

// nonmember binary operator: must declare a parameter for each operand
Sales_item operator+(const Sales_item&, const Sales_item&);

inline bool 
operator==(const Sales_item &lhs, const Sales_item &rhs)
{
    // must be made a friend of Sales_item
    return lhs.units_sold == rhs.units_sold &&
           lhs.revenue == rhs.revenue &&
           lhs.isbn() == rhs.isbn();
}

inline bool 
operator!=(const Sales_item &lhs, const Sales_item &rhs)
{
    return !(lhs == rhs); // != defined in terms of operator==
}

// assumes that both objects refer to the same ISBN
Sales_item& Sales_item::operator+=(const Sales_item& rhs) 
{
    units_sold += rhs.units_sold; 
    revenue += rhs.revenue; 
    return *this;
}

// assumes that both objects refer to the same ISBN
Sales_item 
operator+(const Sales_item& lhs, const Sales_item& rhs) 
{
    Sales_item ret(lhs);  // copy (|lhs|) into a local object that we'll return
    ret += rhs;           // add in the contents of (|rhs|) 
    return ret;           // return (|ret|) by value
}

std::istream& 
operator>>(std::istream& in, Sales_item& s)
{
    double price;
    in >> s.bookNo >> s.units_sold >> price;
    // check that the inputs succeeded
    if (in)
        s.revenue = s.units_sold * price;
    else 
        s = Sales_item();  // input failed: reset object to default state
    return in;
}

std::ostream& 
operator<<(std::ostream& out, const Sales_item& s)
{
    out << s.isbn() << " " << s.units_sold << " "
        << s.revenue << " " << s.avg_price();
    return out;
}

double Sales_item::avg_price() const
{
    if (units_sold) 
        return revenue/units_sold; 
    else 
        return 0;
}
#endif

Sales_data.txt
Hero 1 2 
Tom 2 3
Hero 2 3
Jack 2 3
Hero 3 4

练习10.32-2

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <iterator>
#include "Sales_item.h"

using namespace std;

bool compareISBN(const Sales_item &lhs, const Sales_item &rhs)
{
    return lhs.isbn() < rhs.isbn();
}

bool f(const Sales_item &rhs)
{
    return rhs.isbn() == "Hero";
}
int main()
{   
    ifstream in("Sales_data.txt");
    istream_iterator<Sales_item> sale_in(in),eof;
    ostream_iterator<Sales_item> out_iter(cout, "\n");
    vector<Sales_item> vec(sale_in,eof);
    copy(vec.begin(),vec.end(), out_iter);
    cout << endl;

    sort(vec.begin(),vec.end(),compareISBN);
    copy(vec.begin(),vec.end(), out_iter);
    cout << endl;

    vector<Sales_item> sz_item;
    vector<Sales_item>::iterator it;
    for(it = vec.begin(); it != vec.end();++it)
    {

        if((*it).isbn() == "Hero")
            sz_item.push_back(*it);
    }

    copy(sz_item.begin(),sz_item.end(),out_iter);
    cout << endl;
    cout << accumulate(sz_item.begin(),sz_item.end(),Sales_item("Hero"));
    cout << endl; 

    return 0;   
} 

练习10.33

/*
*练习10.33 
*2015/9/8 
*问题描述：练习10.33：编写程序，接受三个参数：一个输入文件和两个输出文件的文件名。输入文件保存的应该是整数。使用istream_iterator读取输入文件。使用ostream_iterator将奇数写入第一个输出文件，每个值之后都跟一个空格。将偶数写入第二个输出文件，每个值都独占一行。
*说明：要包含 iterator头文件 ，需要构造一个“input”文件放在文件同目录下 
*作者：Nick Feng
*邮箱：[email protected] 
*/

#include <iostream>
#include <vector>
#include <algorithm>
#include <iterator>
#include <fstream>

using namespace std;

void FUN(string input,string odd_output,string even_output)
{
    ifstream in(input);                                        
    //定义输入文件 
    ofstream out_odd(odd_output);                              
    //奇数输出文件 
    ofstream out_even(even_output);                            
    //偶数输出文件 

    istream_iterator<int> int_it(in), eof;
    ostream_iterator<int> out_odd_iter(out_odd," ");            
    //奇数加空格输出  
    ostream_iterator<int> out_even_iter(out_even,"\n");          
    //偶数换行输出 

    vector<int> vec(int_it, eof);                               
    //构造保存输入输出序列的容器 
    vector<int> vec_odd,vec_even;                               
    //奇数容器，偶数容器 

    vector<int>::iterator it = vec.begin();
    while(it  != vec.end())                                   
    //偶数放进偶数容器，奇数放进奇数容器 
    {
        if(*it % 2 == 0)
            vec_even.push_back(*it); 
        else 
            vec_odd.push_back(*it);

        ++it;
    }

    copy(vec_odd.begin(),vec_odd.end(),out_odd_iter);        
    //奇数格式输出 
    copy(vec_even.begin(),vec_even.end(),out_even_iter);      //偶数格式输出 

}

int main()
{
    FUN("input.txt","odd_output.txt","even_output.txt");

    ifstream in("input.txt");        //验证输入数列是否正确 
    ifstream in1("odd_output.txt"); //验证奇数数列是否正确 
    ifstream in2("even_output.txt");//验证偶数序列是否正确 
    string s1,s2,s3;
    while(!in.eof())
    {
        getline(in,s1);
        cout << s1 << endl;              
    }

    while(!in1.eof())
    {
        getline(in1,s2);
        cout << s2 << endl;
    }

    while(!in2.eof())
    {
        getline(in2,s3);
        cout << s3 << endl;
    }

    return 0;
} 

input.txt
1 2  3 4 5 6  7 8 9 

odd_output.txt
1 3 5 7 9 

even_output.txt
2
4
6
6
8