Read & write File

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

int main()
{
    char arr[100];
    ofstream document;
    document.open("file.txt");
    cin.getline(arr, 100);
    document << arr << endl;
    document.close();

    ifstream newdoc;
    newdoc.open("file.txt");
    newdoc >> arr;
    cout << arr;
    newdoc.close();
}