Счетчик слов в текстовом файле

std::ifstream stream("text.txt"};
for(std::string word;stream>>word;)
    if(word.find("a")!=std::string::npos)
        cout<<word<<endl;

#include <iostream>
#include <fstream>
#include <regex>
#include <ctime>
 
#include <map>
 
using namespace std;
 
typedef sregex_token_iterator rti;
typedef pair<string, long long> word_numb;
 
map<string, long long> split(const string& str, const string& delimiters);
vector<word_numb> numberOfIdenticalWords(const string& str);
 
long long substr_count_word(const string& haystack, const string& needle);
 
 
int main(int argc, char *argv[])
{
    string DIR = "D:\\1.txt";
    ifstream fin(DIR);
 
    string s;
    fin.seekg(0, ios::end);
    size_t size = fin.tellg();
 
    s.reserve(size);
    fin.seekg(0, ios::beg);
 
    s.assign((istreambuf_iterator<char>(fin)),
             istreambuf_iterator<char>());
 
    string str = s;
//    str.resize(s.size()*5000);
//    for(int i=0; i<5000; ++i) str += s;
 
    cout << "memory = " << (str.size()/sizeof(char))/1048576 << endl;
 
    size_t start_time = clock();
    vector<word_numb> wn = numberOfIdenticalWords(str);
    size_t end_time = clock();
 
    size_t duration = end_time - start_time;
    cout << "duration msec = " << duration << endl;
 
    /* upd reg
     * memory = 272 mb
     * regex time = 1
     * map time = 133 259
     * sort(vec) time = 1
     *
     * duration time = 133 261
    */
 
 
    /* upd split
     * memory = 272 mb
     * map time = 13 878
     * sort(vec) time = 1
     * duration time = 13 879
     *
     * 133 261 / 13 879 = ~9.6
    */
 
    ofstream fout("D:\\number_of_identical_words.txt");
    for(auto i : wn)
        fout << i.first << " " << i.second << endl;
 
    cout << "\nI finished.\n";
 
    return 0;
}
 
 
map<string, long long> split(const string& str, const string& delimiters) {
    size_t lastPos = str.find_first_not_of(delimiters, 0);
    size_t pos = str.find_first_of(delimiters, lastPos);
 
    map<string, long long> tokens;
    while (string::npos != pos || string::npos != lastPos) {
        string token = str.substr(lastPos, pos - lastPos);
        tokens[token]++;
        lastPos = str.find_first_not_of(delimiters, pos);
        pos = str.find_first_of(delimiters, lastPos);
    }
 
    return tokens;
}
 
 
vector<word_numb> numberOfIdenticalWords(const string& str) {
//    size_t tre0 = clock();
//    vector<string> tokens;
//    std::regex re(R"([\s-,.;:!?\"]+)");
//    rti begin(str.begin(), str.end(), re, -1), end;
//    size_t tre1 = clock();
//    cout << "regex time = " << tre1 - tre0 << endl;
 
//    size_t map0 = clock();
//    map<string, long long> words;
//    while (begin!=end) words[*begin++]++;
//    size_t map1 = clock();
//    cout << "map time = " << map1 - map0 << endl;
 
    size_t map0 = clock();
    map<string,long long> words = split(str, " -,.;:!?\r\n\"");
    size_t map1 = clock();
    cout << "map time = " << map1 - map0 << endl;
 
    size_t vec_words0 = clock();
    vector<word_numb> vec_words(words.begin(), words.end());
    sort(vec_words.begin(), vec_words.end(),
         [](const word_numb& a, const word_numb& b)->bool {
        return a.second > b.second;
    });
    size_t vec_words1 = clock();
    cout << "sort(vec) time = " << vec_words1 - vec_words0 << endl;
 
    return vec_words;
}
 
long long substr_count_word(const string& str, const string& needle) {
    map<string, long long> words = split(str, " -,.;:!?\r\n\"");
    return words[needle];
}
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