Initializing a vector from a text file

Question

I am attempting to write a program which can read in a text file, and store each word in it as an entry in a string type vector. I am sure that I am doing this very wrong, but it has been so long since I have tried to do this that I have forgotten how it is done. Any help is greatly appreciated. Thanks in advance.

Code:

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

using namespace std;

int main()
{
    vector<string> input;
    ifstream readFile;

    vector<string>::iterator it;
    it = input.begin();

    readFile.open("input.txt");

    for (it; ; it++)
    {
        char cWord[20];
        string word;

        word = readFile.get(*cWord, 20, '\n');

        if (!readFile.eof())
        {
            input.push_back(word);
        }
        else
            break;
    }

    cout << "Vector Size is now %d" << input.size();

    return 0;
}

Answer 1

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

using namespace std;

int main()
{
    vector<string> input;
    ifstream readFile("input.txt");
    copy(istream_iterator<string>(readFile), {}, back_inserter(input));
    cout << "Vector Size is now " << input.size();
}

Or, shorter:

int main()
{
    ifstream readFile("input.txt");
    cout << "Vector Size is now " << vector<string>(istream_iterator<string>(readFile), {}).size();
}

I'm not going to explain, because there's about a zillion explanations on StackOverflow already :)