关于C++ primer 4上面的一个文本查询程序！

2025-04-30 22:50:23

推荐回答（3个）

回答1：

//有几个函数是前面几章写过的，但是本章没贴出来
//比如 open_file（），make_plural()，我把open_fie()改成infile.open()了，已经g++测试通过

#include
#include
#include
#include
#include
#include
#include

using namespace std;

class TextQuery {
public:
typedef vector::size_type line_no;
void read_file(ifstream &is){
store_file(is);
build_map();
}

set run_query(const string&) const;

string text_line(line_no) const;

line_no size() const {
return lines_of_text.size();
}

private:
void store_file(ifstream&);
void build_map();
vector lines_of_text;
map > word_map;
};

void TextQuery::store_file(ifstream &is)
{
string line;
while(getline(is,line))
lines_of_text.push_back(line);
}

void TextQuery::build_map()
{
for(line_no iline = 0;iline != lines_of_text.size();++iline){
stringstream istr(lines_of_text[iline]);
string word;
while(istr >> word)
word_map[word].insert(iline);
}
}

set TextQuery::run_query(const string &word) const
{

map >::const_iterator iter;
if((iter = word_map.find(word)) != word_map.end())
return iter -> second;
else{
set tempset;
return tempset;
}
}

string TextQuery::text_line(line_no iline) const
{
return lines_of_text[iline];
}

string make_plural(int size, const string &word, const string &sfx ){
if(size > 1)
return word + sfx;
else
return word;
}

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 "
// don't confound user with text lines starting at 0
<< (*it) + 1 << ") "
<< file.text_line(*it) << endl;
}
}

int main(int argc, char **argv)
{
// open the file from which user will query words
ifstream infile;
if(argc < 2) {
cerr << "./a " << endl;
return EXIT_FAILURE;
}
infile.open(argv[1]);
if (!infile) {
cerr << "cannot open 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 << "enter word to look for, or q to quit: ";
string s;
cin >> 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;
}

回答2：

好像是第十章的那个查询系统不完整，后面有一张吧那个查询系统完整描述了一遍的

当时我也是敲那个程序敲了半天是个错的

回答3：

这个你还要求别人有一本C++ primer 而且是第四版还而且是上。
题都懒得打啊你？唉～