Document Distance C++ version

docdist.cpp

#include <iostream>
#include <fstream>
#include <sstream>
#include <stdexcept>
#include <map>
#include <regex>
#include <set>
#include <cmath>


class WordFreq {

    std::ifstream wordFile;
    std::map<std::string,int64_t> wordCountMap;

    public:

    WordFreq(const std::string& filename) : wordFile(filename) {
        if (!wordFile) {            
            std::ostringstream os;
            os << "Could not open file: " << filename;
            throw std::runtime_error(os.str());
        }
    }

    void countWords() {
        std::string fileContents;
        wordFile.seekg(0,std::ios::end);
        fileContents.resize(wordFile.tellg());
        wordFile.seekg(0,std::ios::beg);
        wordFile.read(&fileContents[0], fileContents.size());
        std::string alNum = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";
        std::ostringstream os;
        for(std::string::iterator current,next = fileContents.begin();
                current != fileContents.end() || next != fileContents.end();){
            if( alNum.find(*next) == std::string::npos) {
                wordCountMap[os.str()]++;
                while ((next != fileContents.end()) && (alNum.find(*next) == std::string::npos)) {
                    next++;
                }
                os.str("");
                current = next;
            } else {
                if( *next <= 'Z' && *next >='A')
                    os << char( *next - ('Z'-'z'));
                else
                    os << (*next);
                next++;
            }
        }
        /*for (std::map<std::string,int64_t>::iterator it = wordCountMap.begin();
                it != wordCountMap.end(); it++) {
            std::cout << "'" << it->first << "' " << it->second << "\n";
        }*/
    }

    const int64_t getWordFreq(const std::string& word) const {
        if (wordCountMap.find(word) != wordCountMap.end()) {
            return wordCountMap.at(word);
        } else {
            return 0;
        }
    }

    const size_t getWordsCount() {
        return wordCountMap.size();
    }

    int64_t getDotProduct(const WordFreq& wordFreq) {
        int64_t acc = 0;
        for (std::map<std::string,int64_t>::iterator it = wordCountMap.begin();
                it != wordCountMap.end(); it++) {
            acc += this->getWordFreq(it->first) * wordFreq.getWordFreq(it->first);
        }
        return acc;
    }

};


int main(int argc, char* argv[]) {
    if (argc < 2) {
        std::cerr << "Please supply at least two file names." << std::endl;
        return 1;
    }
    WordFreq file1Words(argv[1]);
    file1Words.countWords();
    WordFreq file2Words(argv[2]);
    file2Words.countWords();
    std::cout << "Distinct words in file 1 " << file1Words.getWordsCount() << "\n";
    std::cout << "Distinct words in file 2 " << file2Words.getWordsCount() << "\n";
    int64_t t1 = file1Words.getDotProduct(file2Words);
    double t2 = sqrt((double)file1Words.getDotProduct(file1Words));
    double t3 = sqrt((double)file2Words.getDotProduct(file2Words));
    std::cout << "Document distance is " << acos(t1/(t2*t3)) << "\n";
    return 0;
}

how could I open the file