读取Txt，统计某个关键字出现的次数，并将其所在的行打印出来
////// @file TextQuery.cc/// @author miaobeihai(452686191@gmail.com)/// @date 2017-05-01 10:55:06///#include <assert.h>
#include <ctype.h>#include <iostream>
#include <fstream>
#include <sstream>
#include <string> //string--> vector<char>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#include <functional>using std::cout;
using std::endl;
using std::string;
using std::set;
using std::map;
using std::vector;
using std::ifstream;
using std::istringstream;
using std::replace_if;static_assert(sizeof(void*) == 8, "not supported");class TextQuery
{
public:TextQuery();void readFile(const string & filename);void query(const string & word);
private:static const int kInit = 100;vector<string> _lines;map<string, int> _dict;map<string, set<int> > _word2Line;
};TextQuery::TextQuery()
{_lines.reserve(kInit);
}struct NotAlpha //: public std::unary_function<char, bool>
{bool operator()(char ch) const{return (!isalpha(ch));}
};struct IsAlpha : public std::unary_function<char, bool>
{bool operator()(char ch) const{return (isalpha(ch));}
};void test()
{//char * p = NULL;//assert(p != NULL);//使用assert断言,运行时断言//(void)p;//static_assert((p != 0), "nullptr exception");// 编译时断言, 必须要求是一个常量表达式//static_assert(sizeof(p) == 8, "不支持32位系统");//只在编译时起作用，代码不会进入到源码
}void TextQuery::readFile(const string & filename)
{ ifstream ifs(filename);assert(ifs);//assert方法可以多使用，用来判断指针或者对象初始化是否异常string line;int cnt = 0;while(getline(ifs, line)){ _lines.push_back(line);//replace_if(line.begin(), line.end(), std::not1(isalpha), ' ');//Errorreplace_if(line.begin(), line.end(), NotAlpha(), ' ');//replace_if(line.begin(), line.end(), std::not1(IsAlpha()), ' ');cout << cnt << ":" << line << endl;istringstream iss(line);string word;while(iss >> word){++_dict[word];_word2Line[word].insert(cnt);}++cnt;}ifs.close();
}void TextQuery::query(const string & word)
{int freq = _dict[word];cout << word << " occurs " << freq << (freq > 0 ? " times.":" time.") << endl;set<int> & lines = _word2Line[word];for(auto & elem : lines){cout << " (line " << elem + 1 << ")" << _lines[elem] << endl;}
}int main(void)
{TextQuery tq;tq.readFile("china_daily.txt");tq.query("still");return 0;
}