C++ code runs forever and eats memory

Question

It seems to be in MakeData function, as that is what breaks the execution. I am very unsure as to why this is not working, as my instructor and many of my classmates have almost identical execution and it is fine. I know for a fact that an almost identical version of this code, with windows file name, also does not run on windows. I have compiled the code. I have run debuggers. Nothing turns up. The debuggers I have run have just run the code until either very obscure errors turn up or it essentially indicates that the process is in some kind of an infinite loop. Any help would be appreciated!

/*
 *Program Description:A program to sort a series of strings and scores from a file.
 *
 *Programmer:Timothy A. Gass
 *Date:01/17/17
*/

#include <iostream>
#include <string>
#include <math.h>
#include <fstream>
#include <vector>
#include <ctime>

using namespace std;

void makeData(string);
void getData(vector<string> &, vector<int> &, string);

int main(){
  srand(time(0));
  string fname = "/home/tim/dev/c++/chpt9/data.txt";
  vector<string> name;
  vector<int> score;
  makeData(fname);
  getData(name, score, fname);
  for(int i = 0; i < score.size(); i++){
    cout << score[i] << endl;
    cout << name[i] << endl;
  }
  cout << "Press enter to exit." << endl;
  cin.ignore();
  cin.get();
  return 0;
}

void makeData(string fname){
  int rand1, rand2, rand3;
  const int SCORE_MAX_SIZE = 100;
  ofstream make(fname);
  const int PEOPLE_NUM = 50;
  vector<string> firstNames = {
    "Gus",
    "Taneka",
    "Shane",
    "Rosella",
    "Bennett",
    "Filiberto",
    "Khadijah",
    "Mafalda",
    "Rusty",
    "Janiece",
    "Shavonne",
    "Azalee",
    "Enedina",
    "Heidy",
    "Lavelle",
    "Darleen",
    "Ashton",
    "Glynis",
    "Gale",
    "Norene",
    "Madaline",
    "Elvin",
    "Jacqueline",
    "Kristofer",
    "Zachary",
    "Lorretta",
    "Jim",
    "Shanelle",
    "Tonja",
    "Alethia",
    "Kasha",
    "Katheleen",
    "Joyce",
    "Kirstin",
    "Neil",
    "Belkis",
    "Maisha",
    "Doretha",
    "Eliseo",
    "Rhiannon",
    "Annamarie",
    "Latoria",
    "Jerica",
    "Betsey",
    "Delinda",
    "Pamula",
    "Porsha",
    "Fredia",
    "Wilda",
    "Belen"
  };

  vector<string> lastNames = {
    "Best",
    "Shields",
    "Finley",
    "Blankenship",
    "Hobbs",
    "Nichols",
    "Mcneil",
    "Robles",
    "Moyer",
    "Hays",
    "Elliott",
    "Ruiz",
    "Ritter",
    "Gamble",
    "Zamora",
    "Cole",
    "Larson",
    "Ibarra",
    "Choi",
    "Santana",
    "Gray",
    "Crane",
    "Campos",
    "Wright",
    "Morris",
    "Flores",
    "Newman",
    "Santos",
    "Li",
    "Archer",
    "Chavez",
    "Avery",
    "Mora",
    "Liu",
    "Lutz",
    "Miles",
    "Stewart",
    "Austin",
    "Wu",
    "Turner",
    "Brennan",
    "Ferrell",
    "Mcmillan",
    "Whitney",
    "Odonnell",
    "Conley",
    "Maxwell",
    "Stafford",
    "Carlson",
    "Peck"
  };

  for(int i = 0; i < PEOPLE_NUM; i++){
    rand1 = rand()%50;
    rand2 = rand()%50;
    rand3 = rand()%(SCORE_MAX_SIZE+1);
    make << firstNames.at(rand1) + " " + lastNames.at(rand2) << endl;
    make << rand3 << endl;
  }
}

void getData(vector<string> &name, vector<int> &score, string fname){
  ifstream get(fname);
  string str;
  int num;
  if(get.fail()){
    cout << "File could not be opened!" << endl;
  }
  else
   {
     while(!get.eof())
     {
      getline(get, str);
      get >> num;
      cin.ignore();
      name.push_back(str);
      score.push_back(num);
     }
  }
}

The right tool to solve such problems is your debugger. You should step through your code line-by-line *before* asking on Stack Overflow. For more help, please read [How to debug small programs (by Eric Lippert)](https://ericlippert.com/2014/03/05/how-to-debug-small-programs/). At a minimum, you should \[edit] your question to include a [Minimal, Complete, and Verifiable](http://stackoverflow.com/help/mcve) example that reproduces your problem, along with the observations you made in the debugger. — πάντα ῥεῖ, Jan 31 '17 at 20:17
@MikelF: Why should it be `"//home//tim//def//c++//chpt9//data.txt"`? — Lightness Races in Orbit, Jan 31 '17 at 20:17
@MikelF '/ is not an escape character. You must be thinking of '\'. — molbdnilo, Jan 31 '17 at 20:17
_"I am very unsure as to why this is not working, as my instructor and many of my classmates have almost identical execution and it is fine"_ So what are the differences between the working and non-working versions? — Lightness Races in Orbit, Jan 31 '17 at 20:18
Read about why `while(!get.eof())` is wrong [here](http://stackoverflow.com/questions/5605125/why-is-iostreameof-inside-a-loop-condition-considered-wrong). If your teacher taught you to write that, tell them they're wrong. — molbdnilo, Jan 31 '17 at 20:21
And what in the world is `cin.ignore();` doing in `getData`? — molbdnilo, Jan 31 '17 at 20:23
Don't mix getline and operator>>. Try do getline twice, and convert the string get from the second line to an int instead. — greedy52, Jan 31 '17 at 20:26
@molbdnilo He not only told me to write it. He wrote it himself. I don't know why myself. Thanks for your help! — Tim Gass, Feb 01 '17 at 01:24
@LightnessRacesinOrbit I suppose you could to try to write a program that finds out whether a given program runs forever or not :DDD — iolo, Feb 02 '17 at 19:46
@iolo: [No, you couldn't](https://en.wikipedia.org/wiki/Halting_problem). — Lightness Races in Orbit, Feb 02 '17 at 19:49

score 0 · Answer 1 · edited Feb 03 '17 at 10:09

0

The comment made by Xin Huang was correct. It turns out the use of getline and cin resulted in some form of infinite loop that would eat memory, until the computer would eventually crash. I still have no idea why there is no solution to this, or why using cin and getline together could have such terrible consequences, especially considering there were really no error codes. Even still, replacing cin with getline in the getData function and then converting back to integer yields a clean program.

edited Feb 03 '17 at 10:09

Lightness Races in Orbit

378,754
76
643
1,055

answered Feb 02 '17 at 19:10

Tim Gass

383
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9

_"I still have no idea why there is no solution to this, or why using cin and getline together could have such terrible consequences, especially considering there were really no error codes"_ There _was_ an error condition; you didn't check for it (you only check for EOF). That's the bug. Don't loop with `while (!get.eof())`, as I said before and in fact has been said a million times on SO! molbdnilo linked you to a page that explains why. – Lightness Races in Orbit Feb 03 '17 at 10:09

C++ code runs forever and eats memory

1 Answers1