使用tuple返回多个值

17.4编写并测试findbook函数

#include<iostream>

#include<vector>

#include<string>

#include<tuple>

#include<algorithm>

#include"Sales_data.h"

using namespace std;

typedef tuple<vector<Sales_data>::size_type,vector<Sales_data>::const_iterator,vector<Sales_data>::const_iterator> matches;



vector<matches> findbook(const vector<vector<Sales_data>> &files,const string &book)

{

    vector<matches> ret;

    for(auto it=files.begin();it!=files.end();++it)

    {

        auto found=equal_range(it->begin(),it->end(),book,compareIsbn);

        if(found.first!=found.second)

            ret.push_back(make_tuple(it-files.begin(),found.first,found.second));

    }

    return ret;

}



void reportResult(istream &in,ostream &os,const vector<vector<Sales_data>> &files)

{

    string s;

    while(in>>s)

    {

        auto trans=findbook(files,s);

        if(trans.empty())

        {

            cout<<s<<" not found in any stores "<<endl;

            continue;

        }

        for(const auto &store:trans)

        {

            os<<"stores "<<get<0>(store)<<" sales: "

                <<accumulate(get<1>(store),get<2>(store),Sales_data(s))

                <<endl;

        }

    }

}



int main()

{



}

17.5重写findbook，令其返回一个pair，包含一个索引和一个迭代器pair。

typedef pair<vector<Sales_data>::size_type,pair<vector<Sales_data>::const_iterator,vector<Sales_data>::const_iterator>> match;

vector<match> findbook1(const vector<vector<Sales_data>> &files,const string &book)

{

    vector<match> ret;

    for(auto it=files.begin();it!=files.end();++it)

    {

        auto found=equal_range(it->begin(),it->end(),book,compareIsbn);

        if(found.first!=found.second)

            ret.push_back(make_pair(it-files.begin(),make_pair(found.first,found.second)));

    }

    return ret;

}