#include <cstdlib>
#include <string>
#include <vector>
#include <fstream>
#include <iostream>
#include <map>
#include <sstream>
#include <algorithm>
#include <utility>
#include <set> // make_pair
using namespace std;
#include "fileIOs_wordPairs.h"

/**
* read file and split it into sentences then push them in to a vector
* @param fname
* @param sentences
* @return
*/
bool sentenceSplitter(string& fname, vector<string>& sentences) {
// read all file into a string
fstream in;
in.open(fname.c_str(), ios::in);
if (in.is_open() == false) { // the file cannot be open
   return false;
}
/*
string content;
content.assign(istreambuf_iterator<char> (in), istreambuf_iterator<char>());
*/

// read each character from thee input stream

string sentence = "";
string delimiter = ".?";

string paragraph;
// read line
while (getline(in, paragraph)) {
   if (paragraph.empty() == false) {// it should not an empty line
         size_t index = paragraph.find_first_of(delimiter);
         size_t start = 0;
         // try to get sentence from paragraph
         while (index != string::npos) {
            sentence = paragraph.substr(start, index - start);
            sentences.push_back(sentence);
            // moveto the next sentence head
            for (size_t i = index; i < paragraph.length(); i++) {

               if (isalpha(paragraph[i])) {
                     start = i;
                     break;
               }
            }
            index = paragraph.find_first_of(delimiter, index + 1);
         }
   }
}

Using the data file, “FactoryData” 300 450 500 210 510 600 7...