C++ Primer 10.6

来源：互联网发布：赚佣金的软件编辑：程序博客网时间：2024/05/17 04:17
#include <iostream>#include <string>#include <map>#include <set>#include <vector>#include <fstream>#include <sstream>using namespace std;class TextQuery{public:typedef vector<string>::size_type line_no;void read_file(ifstream &is){store_file(is);build_map();}//用于从文件中读取一行，保存在vector中，并把每个单词存放在行号map中 set<line_no> run_query(const string&) const;//保存行号 string text_line(line_no) const;private:vector<string> line_of_text;//用于储存整个输入文件的副本map< string,set<line_no> > word_map;//用于储存每个单词，及其所在行setvoid store_file(ifstream&);//读入文件，存入vector中 void build_map();//将每一行分解成单词，创建map对象，并记录出现的行号 };void TextQuery::store_file(ifstream &is){string textline;while(getline(is,textline))line_of_text.push_back(textline);}void TextQuery::build_map(){for(line_no line_num = 0; line_num != line_of_text.size();++line_num){istringstream line(line_of_text[line_num]);string word;while(line>>word)word_map[word].insert(line_num);}}set<TextQuery::line_no> TextQuery::run_query(const string &query_word) const{map< string,set<line_no> >::const_iterator loc = word_map.find(query_word);if(loc == word_map.end())return set<line_no>();elsereturn loc->second;}string TextQuery::text_line(line_no line) const{if(line < line_of_text.size())return line_of_text[line];cout<<"line number out of range"<<endl;}//判断字符出现次数是否为1 string make_plural (size_t ctr , const string &word , const string &ending) {     return ( ctr == 1 ) ? word : word + ending; } void print_results(const set<TextQuery::line_no>& locs,const string& sought,const TextQuery &file){typedef set<TextQuery::line_no> line_nums;line_nums::size_type size = locs.size();cout<<endl;cout<<sought<<" occurs "<<size<<" "<<make_plural(size,"time","s")<<endl;line_nums::const_iterator it = locs.begin();for(;it != locs.end(); ++it){cout<<" (line "<<(*it)+1<<") "<<file.text_line(*it)<<endl;}}int main(){ifstream infile("world.txt");TextQuery tq;tq.read_file(infile);while(true){cout<<"输入要查询的单词：";string word;cin>>word;if(!cin || word == "quit")break;set<TextQuery::line_no> locs = tq.run_query(word);print_results(locs,word,tq);} system("pause");}
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