#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
#include <pthread.h>
#include <unistd.h>
#include "squarethis.h"
using namespace std;

int main (int argc, char **argv) {

     srand (time(NULL));
     id = new int[SIZE];
     squares = new int[SIZE];
     th = new pthread_t [SIZE]; //array of threads
     for (int i=0; i < SIZE; i++) {
        id[i] = i;
        pthread_create (&th[i],nullptr,squareself,&id[i]);
        /*
          the first argument is a pointer to a thread (actually a thread type)
          th is an array of threads.  th[i] is one specific thread in the array
          &th[i] is a pointer to that specific thread

          The second argument defines the "attributes" for the thread.  A null pointer indicates
          the default attributes, which is all we are really going to use.

          The third argument is a function pointer to the method the thread will
          run.  It must be a method takes one void * argument and returns void *

          The fourth argument is the parameter that will be passed to the method
          specified in the third argument
        
        
        */
     }
     for (int i=0; i < SIZE; i++)
        pthread_join (th[i],nullptr);//waiting until the threads die
    //the first argument is the thread we're waiting for
    //The second argument is where we put the return value of the thread (which is null in this case)

    for (int i=0; i < SIZE; i++)
        cout << squares[i] << endl;
    cout << endl;
    delete[] id;
    delete[] squares;
    delete[] th;
    return 0;
}

void *squareself (void * a) { //thread methods ALWAYS take a void * pointer and ALWAYS return a void * pointer
    //in this case they will take a memory location containing an integer I want to square
    //The method will square that integer and then return null

    //void * is a pointer to anything.  It can point to an int or char or struct
    //or anything random and it works without casting.

    int t = 1+rand()%10; //get a random int between 1 and 10
    sleep (t);
    int idnum = *(int *)a;
    squares[idnum] = idnum*idnum;
 //   cout << "Squared " << idnum << endl;
    return nullptr;


}