#include "stdio.h"
#include "stdlib.h" //including a new library today, for rand function
#include <fstream> //another new one, for file input and output operations
#include <iostream>
#include "math.h"
#include "string.h" //another new one

using namespace std;

int main ( int argc, char** argv ) {
  
  //today's lesson #1: for and while loops
  for ( int i = 0; i < 100; i++ ) { //create variable integer i and initialize to 0
    cout << i << endl; //can do many other things; can have multiple lines
  }
  srand(atoi(argv[1])); //initialize the random number seed
  long randomNumber = rand(); //long is a bigger type of integer than int is
  while ( randomNumber > long(1e8) ) {
    randomNumber = rand(); //keep on overwriting the initial value
  }
  cout << randomNumber << endl;

  //lesson #2: how to write output to a text file
  ofstream myfile; //much easier than in C
  myfile.open("example_output.dat",ios::app); //must open and name it (myfile is var name)
  myfile << "Writing this to a file." << "\t" << randomNumber << endl; //overwrites
  myfile.close();//always close all of your files before exiting, when done
  
  //lesson #3: how you can read from an existing file
  string line;
  ifstream file("error.txt");
  if ( file.is_open() ) {
    while ( getline ( file, line ) ) {
      cout << line << endl;
    }
    file.close();
  }
  else cout << "Unable to open file!" << endl;

  //lesson #4: strings, characters, and operations with them
  string name = "Hello world,";
  string continuation;
  continuation = " watch out for me! I'm coming.";
  name.append(continuation); //much easier than equivalent in C
  cout << name << endl;
  char letter = 'A'; //the grade you want to get :)
  printf("I am lonely, just the letter %c.\n",letter);
  
  //Next: debug with cout statements, string/file append, Gauss/exp rand's
  return 1;

}