C++的一个简单的文本查询程序.doc

本篇实例的目的是做一个简单的文本查询程序，通过编码过程有益于您对vector, map, set的基本掌握。/*目的：一个简单的文本查询程序*作用：程序将读取用户指定的任意文本文件，然后允许用户从该文件中查找单词。*查询的结果是该单词出现的次数，并列出每次出现所在的行。*如果某单词在同一行中多次出现，程序将只显示该行一次。*行号按升序显示，即第 7 行应该在第 9 行之前输出，依此类推。*/*思路：*1.使用一个 vector 类型的对象存储整个输入文件的副本。* 输入文件的每一行是该 vector 对象的一个元素。* 因而，在希望输出某一行时，只需以行号为下标获取该行所在的元素即可。*2.将每个单词所在的行号存储在一个 set 容器对象中。* 使用 set 就可确保每行只有一个条目，而且行号将自动按升序排列。*3.使用一个 map 容器将每个单词与一个 set 容器对象关联起来，* 该 set 容器对象记录此单词所在的行号。*/TextQuery.H文件#ifndef TEXTQUERY_H#define TEXTQUERY_H#include #include #include #include #include #include #include #include class TextQuery / as beforepublic: / typedef to make declarations easier typedef std:string:size_type str_size; typedef std:vector:size_type line_no; /* interface: * read_file builds internal data structures for the given file * run_query finds the givenwordand returns set of lines on which it appears * text_line returns a requested line from the input file */ void read_file(std:ifstream &is) store_file(is); build_map(); std:set run_query(const std:string&) const; std:string text_line(line_no) const; str_size size() const return lines_of_text.size(); void display_map(); / debugging aid: print the mapprivate: / utility functions used by read_file void store_file(std:ifstream&); / store input file void build_map(); / associated each word with a set of line numbers / remember the whole input file std:vector lines_of_text; / map word to set of the lines on which it occurs std:map std:string, std:set word_map; / characters that constitute whitespace static std:string whitespace_chars; / canonicalizes text: removes punctuation and makes everything lower case static std:string cleanup_str(const std:string&);#endifTextQuery.CPP 文件#include TextQuery.h#include #include #include #include #include #include #include #include #include #include using std:istringstream;using std:set;using std:string;using std:getline;using std:map;using std:vector;using std:cerr;using std:cout;using std:cin;using std:ifstream;using std:endl;using std:ispunct;using std:tolower;using std:strlen;using std:out_of_range;string TextQuery:text_line(line_no line) const if (line word) / add this line number to the set; / subscript will add word to the map if its not already there word_mapcleanup_str(word).insert(line_num); setTextQuery:run_query(const string &query_word) const / Note: must use find and not subscript the map directly / to avoid adding words to word_map! mapstring, set :const_iterator loc = word_map.find(cleanup_str(query_word); if (loc = word_map.end() return set(); / not found, return empty set else / fetch and return set of line numbers for this word return loc-second;void TextQuery:display_map() map string, set :iterator iter = word_map.begin(), iter_end = word_map.end(); / for each word in the map for ( ; iter != iter_end; +iter) cout word: first ; / fetch location vector as a const reference to avoid copying it const set &text_locs = iter-second; set:const_iterator loc_iter = text_locs.begin(), loc_iter_end = text_locs.end(); / print all line numbers for this word while (loc_iter != loc_iter_end) cout *loc_iter; if (+loc_iter != loc_iter_end) cout , ; cout n; / end list of output this word cout endl; / finished printing entire map/ lower-case to upper-casestring TextQuery:cleanup_str(const string &word) string ret; for (string:const_iterator it = word.begin(); it != word.end(); +it) if (!ispunct(*it) ret += tolower(*it); return ret;主函数#include TextQuery.h#include #include #include #include #include #include #include #include #include using std:set;using std:string;using std:map;using std:vector;using std:cerr;using std:cout;using std:cin;using std:ifstream;using std:endl;string make_plural(size_t, const string&, const string&);ifstream& open_file(ifstream&, const string&);void print_results(const set& locs, const string& sought, const TextQuery &file) / if the word was found, then print count and all occurrences typedef set line_nums; line_nums:size_type size = locs.size(); cout n sought occurs size make_plural(size, time, s) endl; / print each line in which the word appeared line_nums:const_iterator it = locs.begin(); for ( ; it != locs.end(); +it) cout t(line / dont confound user with text lines starting at 0 (*it) + 1 ) file.text_line(*it) endl; / program takes single argument specifying the file to queryint main() / open the file from which user will query words ifstream infile; if (!open_file(infile, Tanky_Woo.txt) cerr No input file! endl; return EXIT_FAILURE; TextQuery tq; tq.read_file(infile); / builds query map / iterate with the user: prompt for a word to find and print results / loop indefinitely; the loop exit is inside the while while (true) cout s; / stop if hit eof on input or a q is entered if (!cin | s = q) break; / get the set of line numbers on which this word appears set locs = tq.run_query(s); / print count and all occurrences, if any print_results(locs, s, tq); return 0;string make_plural (size_t ctr , const string &word ,const string &ending) return ( ctr = 1 ) ? word : word + ending;ifstream& open_file(ifstream &in, const st