读书笔记（C++）——【关联容器】

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#include<iostream>#include<fstream>#include<sstream>#include<string>#include<cctype>#include<vector>#include<map>#include<set>#include <stdexcept>#include<stdlib.h>using namespace std;//map//表10 - 5 insert1,m.insert(e);2,m.insert(beg,end);3,m.insert(iter,e)//10.3.4//使用下标访问    map<string,int> word_count;    string word;    while(cin>>word)        ++word_count[word];    word_count.insert(make_pair("Anna",1));or  typedef map<string,int>::value_type calType;    word_count(valuType("Anna",1));//10.3.5 map insert使用    map<string,int> word_count;    while(cin>>word)    {        pair<map<string,int>::iterator,bool> ret =                        word_count.insert(make_pair(word,1));        if(!ret.second)            ++ret.first->second;/    }//表10 — 6 不修改map对象的查询操作m.count(k);m.find(k);    int occurs = 0;    map<string,int>::iterator it = word_count.find("foobar");    if(it != word_count.end())        occurs = it->second;//10.3.7 map中删除对象//表10 - 7m.erase(k);//返回1 or 0m.erase(p);//p为迭代器；m.erase(b,e);//10.3.8 遍历    map<string,int>::iterator map_it = word_count.begin();    while(map_it != word_count.end())        {        cout<<map_it->first<<":"<<map_it->second<<endl;        ++map_it;        }//10.3.9 单词转换int main(int argc,char **argv){    map<string,int> trans_map;    string key,value;    if(argc != 3)        throw runtime_error("wrong number of arguments");    ifstream map_file;    if(!open_file(map_file,atgv[1]))        throw runtime_error("no transformation file");    while(map_file>>key>>value)        trans_map.insert(make_pair(key,value));    ifstream input;    if(!open_file(input,argv[2]))        throw runtime_error("no input file");    while(getline(input,line))    {        istringstream stream(line);        string word;        bool firstword = true;        while(stream>>word)        {            map<string,string>::const_iterator map_it =                                trans_map.find(word);            if(map_it != trans_map.end())                word = map_it->second;            if(firstword)                firstword = false;            else                cout<<" ";            cout<<word;        }        cout<<endl;    }}//10.4.1 set定义和使用    vector<int> ivec;    for(int i = 0;i != 10;i++)    {        ivec.push_back(i);        ivec.push_back(i);    }    set<int> iset(ivec.begin(),ivec.end())    cout<<ivec.size()<<endl;//prints 20;    cout<<iset.size()<<endl;//prints 10;//在set中添加元素    set<string> set1;    set1.insert("the");    set1.insert("and");or    set<int> set2;    set2.insert(ivec.begin(),ivec.end());//获取元素    iset.find(1)//returns iterator that refers to the element with the key == 1    iset.find(11)//returns iterator == iset.end();    iset.count(1)//returns 1;    iset.count(11)//returns 0;    set<int>::iterator set_it; = iset.find(1);    *set_it = 11;//error:keys in a set are read_only;    cout<<*set_it<<endl;//10.4.2 单词排除集void restricted_wc(ifstream &remove_file,                   map<string,int> &cord_count){    set<string> excluded;    string remove_word;    while(remove_file>>remove_word)        excluded.insert(remove_word);    string word;    while(cin>>word)        if(!excluded.count(word))        ++word_count[word];}//10.5 multimap 和 multiset//10.5.1 元素添加和删除    authors.insert(make_pair(        string("Barth,John")        string("Sot-Weed Factor")));    authors.insert(make_pair(        string("Barth,John")        string("Lost in the Funhouse")));    multimap<string,string> authors;    string search_item("Kazuo Ishiguro");    multimap<string,string>::size_type cnt =                    authors.erase(search_item);//在multimap和multiset中查找元素//1.使用find和count操作    string search_item("WG");    typedef multimap<string,string>::size_type sz_type;    sz_type entrise = authors.count(search_item);    multimap<string,string>::iterator iter =                        authors.find(search_item);    for(sz_type cnt = 0;cnt != entrise;++cnt,++iter)        cout<<iter->second<<endl;//2.面向迭代器解决//表10 - 8 返回迭代器的关联容器操作m.lower_bound(K)    //返回一个迭代器，指向键不小于K的第一个元素m.upper_bound(K)    //返回一个迭代器，指向键大于k的第一个元素m.equal_range(k)    //返回一个迭代器的pair对象                    //它的first成员等价于m.lower_bound(k),second成员等价于m.upper_bound(k)//    typedef multimap<string,string>::iterator authors_iter;    authors_iter beg = authors.lower_bound(search_item);                _end = authors.upper_bound(search_item);    while(beg != _end)    {        cout<<beg->second<<endl;        ++beg;    }//直接调用equal_range解决    pair<authors_iter,authors_iter>            pos = authors.equal_range(search_item);    while(pos.first != pos.second)    {        cout<<pos.first->second<<endl;        ++pos.first;    }//容器综合应用：文本查询程序#include<iostream>#include<fstream>#include<sstream>#include<string>#include<cctype>#include<vector>#include<map>#include<set>#include <stdexcept>#include<stdlib.h>class TextQuery{public:    typedef std::vector<std::string>::size_type line_no;    void read_file(std::ifstream &is)    {        store_file(is);build_map();    }    std::set<line_no> run_query(const std::string&) const;    std::string text_line(line_no) const;private:    void store_file(std::ifstream&);    void build_map();    std::vector<std::string> lines_of_text;    std::map<std::string,std::set<line_no> > word_map;};void TextQuery::store_file(std::ifstream &is){    std::string textline;    while(getline(is,textline))        lines_of_text.push_back(textline);}void TextQuery::build_map(){    for(line_no line_num = 0;        line_num != lines_of_text.size();                                ++line_num)    {        std::istringstream line(lines_of_text[line_num]);        std::string word;        while(line>>word)            word_map[word].insert(line_num);    }}std::set<TextQuery::line_no>TextQuery::run_query(const std::string &query_word) const{    std::map<std::string,std::set<line_no> >::const_iterator                                loc = word_map.begin();    if(loc == word_map.end())        return std::set<line_no>();    else        return loc->second;}std::string TextQuery::text_line(line_no line)const{    if(line<lines_of_text.size())        return lines_of_text[line];    throw std::out_of_range("line number out of range");}void print_results(const std::set<TextQuery::line_no>& locs,                  const std::string& sought,const TextQuery &file);                  std::ifstream& open_file(std::ifstream &in,const std::string &file){    in.close();    in.clear();    in.open(file.c_str());    return in;}std::string make_plural(size_t ctr,const std::string &word,const std::string &ending){    return (ctr==1)?word:word + ending;}int main(int argc,char **argv){    std::ifstream infile;    if(argc < 2 || !open_file(infile,argv[1]))    {        std::cerr<<"No input file!"<<std::endl;        return EXIT_FAILURE;    }    TextQuery tq;    tq.read_file(infile);    while(true)    {        std::cout<<"enter word to look for,or q to quit: ";        std::string s;        std::cin>>s;        if(!std::cin || s == "q")        break;        std::set<TextQuery::line_no> locs = tq.run_query(s);        print_results(locs,s,tq);    }    return 0;}void print_result(const std::set<TextQuery::line_no>& locs,                  const std::string& sought,const TextQuery &file){    typedef std::set<TextQuery::line_no> line_nums;    line_nums::size_type sz = locs.size();    std::cout<<"\n"<<std::cout<<sought<<" occurs"<<sz<<" "                    <<make_plural(sz,"time","s")<<std::endl;    line_nums::const_iterator it = locs.begin();    for(;it != locs.end();++it)    {        std::cout<<"\t(line "            <<(*it) + 1<<") "            <<file.text_line(*it)<<std::endl;    }}
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