c++ - Count the number of times each word occurs in a file

Question

Hi I am writing a program that counts the number of times each word occurs in a file. Then it prints a list of words with counts between 800 and 1000, sorted in the order of count. I am stuck on keeping a counter to see if the first word matches the next until a new word appears. In the main I am trying to open the file, read each word by word and call sort in the while loop to sort the vector. Then, in the for loop go through all the words and if the first word equals the second count++. I don't think that is how you keep a counter.

Here is the code:

#include <string>
#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <set>

using namespace std;

vector<string> lines;
vector<int> second;
set<string> words;
multiset<string> multiwords;

void readLines(const char *filename)
{
    string line;
    ifstream infile;
    infile.open(filename);
    if (!infile)
    {       
        cerr << filename << " cannot open" << endl; 
          return; 
    }       
    getline(infile, line);
    while (!infile.eof())
    {
        lines.push_back(line);
        getline(infile, line);
    }  
    infile.close();
}

int binary_search(vector<string> &v, int size, int value)
{
    int from = 0;
    int to = size - 1;
    while (from <= to)
    {  
        int mid = (from + to) / 2;
        int mid_count = multiwords.count(v[mid]);
        if (value == mid_count) 
            return mid;
        if (value < mid_count) to = mid - 1;
        else from = mid + 1;
    }
   return from;
}

int main() 
{
    vector<string> words;
    string x;
    ifstream inFile;
    int count = 0;

    inFile.open("bible.txt");
    if (!inFile) 
    {
        cout << "Unable to open file";
        exit(1);
    }
    while (inFile >> x){
        sort(words.begin(), words.end());
    }

    for(int i = 0;i < second.size();i++)
    {
        if(x == x+1)
        {
            count++;
        }
        else
            return;
    }
    inFile.close();
}

Answer 1

He. I know bluntly showing a solution is not really helping you. However.

I glanced through your code and saw many unused and confused bits. Here's what I'd do:

#include <algorithm>
#include <fstream>
#include <functional>
#include <iostream>
#include <iterator>
#include <map>
#include <string>
#include <vector>

using namespace std;

// types
typedef std::pair<string, size_t> frequency_t;
typedef std::vector<frequency_t> words_t;

// predicates
static bool byDescendingFrequency(const frequency_t& a, const frequency_t& b)
{ return a.second > b.second; }

const struct isGTE // greater than or equal
{ 
    size_t inclusive_threshold;
    bool operator()(const frequency_t& record) const 
        { return record.second >= inclusive_threshold; }
} over1000 = { 1001 }, over800  = { 800 };

int main() 
{
    words_t words;
    {
        map<string, size_t> tally;

        ifstream inFile("bible.txt");
        string s;
        while (inFile >> s)
            tally[s]++;

        remove_copy_if(tally.begin(), tally.end(), 
                       back_inserter(words), over1000);
    }

    words_t::iterator begin = words.begin(),
                      end = partition(begin, words.end(), over800);
    std::sort(begin, end, &byDescendingFrequency);

    for (words_t::const_iterator it=begin; it!=end; it++)
        cout << it->second << "" << it->first << endl;
}

Authorized Verion:

993 because
981 men
967 day
954 over
953 God,
910 she
895 among
894 these
886 did
873 put
868 thine
864 hand
853 great
847 sons
846 brought
845 down
819 you,
811 so

Vulgata:

995 tuum
993 filius
993 nec
966 suum
949 meum
930 sum
919 suis
907 contra
902 dicens
879 tui
872 quid
865 Domine
863 Hierusalem
859 suam
839 suo
835 ipse
825 omnis
811 erant
802 se

Performance is about 1.12s for for both files, but only 0.355s after drop-in replacing map<> with boost::unordered_map<>