#include<iostream>
using namespace std;

/* In C, I'd have written something like this:
 * void apply_to_all(int *list, int (*function)(int), size_t length){
 * But in C++, when you capture the parameter sum, for task 2, that changes the type
 * of the function to something that can't really be described in C syntax, thus the use
 * of the template.  You don't have to explicitly instantiate the template, though, just 
 * use it like a normal function, and it'll work.  See the example. */
template<class ftype>
void apply_to_all(int *list, ftype function, size_t length){
	for(int i = 0; i < length; i++)
		list[i] = function(list[i]);
}

string to_string(int *array, size_t length){
	string retval = "[";
	for(int i = 0; i < length; i++)
		retval += (i+1) < length? to_string(array[i]) + ", ":to_string(array[i]);
	retval += "]";
	return retval;
}

int square(int x){
	return x*x;
}

int main(){
	int demo_array[] = {5, 10, 15, 20};
	cout << "Initial Array:  " << to_string(demo_array, 4) << endl;

	/* Here's an example of how apply_to_all works with a non-lambda function */
	apply_to_all(demo_array, square, 4);
	cout << "With all numbers squared:  " << to_string(demo_array, 4) << endl;
	/* Now let's divide each number by 10, with a lambda function */ 
	apply_to_all(demo_array, [](int x){return x/10;}, 4);
	cout << "With each number divided by 10:  " << to_string(demo_array, 4) << endl;
	/* If it makes you feel better about it, you can space it out with more lines.
 	 * We'll multiply each number by 5 this time */
	apply_to_all(demo_array, 
	[](int x){
		return x * 5;
	}
	, 4); /* But now, the end looks a little goofy (this is the end of the call to apply_to_all); */
	cout << "Multiplied by 5:  " << to_string(demo_array, 4) << endl;

	/* Enough examples, your turn! */

	int array[] = {3, 6, 9, 12, 15, 18, 21, 24, 27, 30}; // Length is 10	
	cout << "Initial test Array:  " << to_string(array, 10) << endl;
	
	/* Task 1:  Divide each number by 3 */
	
	cout << "Divided by 3:  " << to_string(array, 10) << endl;

	/* Task 2:  Add up all the numbers in the array
 	 * Note:  You'll have to capture sum for this one */
	int sum = 0;
	
	cout << "The sum is:  " << sum << endl;

	/* Task 3:  For each number, if it's odd, multiply it by 100 */
	
	cout << "With each odd number multipled by 100:  " << to_string(array, 10) << endl;

	/* Task 4:  Replace the middle 4 numbers with a 4 
 	 * Note:  You'll have to start partway through (array + ...) and specify less than the full length */
	
	cout << "With 4's in the middle:  " << to_string(array, 10) << endl;
	return 0;
}