Common Phrases Loop

#include <iostream>
#include <fstream>
#include <vector>
#include <cstring>
using namespace std;

int main () {
  ifstream f;
  f.open ("nospace2.txt");
  struct data{
    char *digits;
    int repeats;
  };
  for(int w = 9; w < 3201; w = w + 8){
  char *b;
  b = new char[w];
  b[(sizeof(b)/sizeof(*b))] = 0;

  vector<data> combo;
  int count = 0;
  while(f.read(b, w - 1)){
    int found = 0;
    //printf("%s  ", b);
    for(int j = 0; j < combo.size(); j++){
      //printf("comparing b = %s and digits = %s ", b, combo[j].digits);
      if (strcmp(b, combo[j].digits) == 0) {
          combo[j].repeats++;
          found = 1;
          //printf("They match!");
      }
      //printf("\n");
    }
    if(found == 0){
      combo.push_back(data());
      combo[count].digits = new char[w];
      strcpy(combo[count].digits, b);
      combo[count++].repeats = 1;
      //printf("no match was found, setting combo[%d].repeats = %d and digits = %s\n", count - 1, combo[count - 1].repeats, combo[count - 1].digits); //ignore
    }
  //  f.seekg((-w+9), f.cur);
  }
  f.clear();
  f.seekg(0);
  int numoftwos = 0;
  int pos = 0;
  for(int k = 0; k < combo.size(); k++){
    if(combo[k].repeats == 2){
      numoftwos++;
      pos = k;
    }
  }
  if(numoftwos == 1){
    printf("It worked with n = %d, value is %s\n", w, combo[pos].digits);
    //break;
  }else{
    printf("Failed for n = %d, numoftwos = %d\n", w, numoftwos);
  }
  delete [] b;
  combo.clear();
  vector<data>().swap(combo);
}
/*
  vector<int> max;
  vector<int> pos;

  for (int k = 0; k < combo.size(); k++) {
    max.push_back(-5000000);
    pos.push_back(0);
    for(int i = 0; i < combo.size(); i++){
      //printf("%d\n", combo[i][0]); //ignore
      if(combo[i].repeats > max[k]){
        max[k] = combo[i].repeats;
        pos[k] = i;
      }
    }
    printf("%s occured %d times\n", combo[pos[k]].digits, max[k]);
    combo[pos[k]].repeats = -1;
  }
*/
  f.close();
  return 0;
}