/* This program demonstrates arrays. It shows how arrays are declared, initialized, used and copied.
 * It also shows how the random number generator available with C++ is used.
 */
#include<iostream>
#include<cstdlib> //for the random number generator

int main()
{
	// declaring an integer array using set notation
	// If the array is small enough, and we know, for sure, what values
	// are in the array, we can use set notation
	int arr[10] = {1, 4, -3, 5, 18, -9, 56, 12};
	// If we don't give it enough values, the array is filled out with 0's
	// If we give too many elements, it will cause an error
	// int numbers[5] = {1,2,3,4 ,5,6,7,8}; //error
	
	/*We cannot split this up into 2 lines, like we culd for single varibales.*/

	//We use the index notation to access individual variables.
	cout<<arr[1]<<"\t"<<arr[6]<<"\t"<<arr[9]<<endl;
	
	//If we exceed the index, it will either print junk, or result in a segfault
	//That depends on the index, and whether that memory location is accessible.
	cout<<arr[19]<<endl; // Will most likely print junk
	//cout<<arr[9999999999]<<endl; //Will most likely segfault
	
	/*Using arrays.
 	 * We're going to calculate the average of 1000 grades
 	 */

	const int size = 1000;
	double grades[size]; //Declare this way if we don't know values beforehand
	//set up RNG
	srand(time(0));

	//assign random value to grades.
	//rand() gives you a value between 0 and RAND_MAX, a machine specific constant
	//We then convert it to a value between 0 and 100
	
	//We use for loops to poulate the array. Arrays and for loops go very well together.
	for(int i=0; i<size; i++)
		grades[i] = rand() % 100;

	//Calculate average
	double sum = 0;
	for(int i =0; i<size; i++)
		  sum = sum + grades[i];

	cout<<"The vaerage is "<< sum/size<<endl;

	//Arrays of chars are special cases. They're also called C-style strings
	
	//We can use set notation to initialize a char array
	//We have to null terminate it, by adding the character '\0' at the end
	char name[] = {'S','p','o','n','g','e','b','o','b','\0'};

	//We can also just initialize it with a string literal
	char job[] = "Cook at Krusty Krab"; // We don't need the '\0' here

	//Printing an array without specifying an index would print its starting address
	cout<<"arr is "<<arr<<endl;

	//However, char arrays' contents can be printed that way
	cout<<name<<" works as a "<<job<<endl;

	/* Copying arrays
 	 * If we just assign one array variable to another, it will act as a reference variable.
 	 * To create a new array with the same data, we have to copy each individual cell.
 	 * This process if called a deep copy.
 	 */
	int alsoArr[10];
	for(int i=0;i<10;i++)
		alsoArr[i] = arr[i];

	cout<<alsoArr[3]<<endl;

	arr[4] = 20;//changing values in arr

	cout<<"Arr: "<<arr[4]<<"\tAlsoArr: "<<alsoArr[4]<<endl;
	//Will print 2 separate values, since they are different arrays.
	return 0;
}