quick question

[MaseratiDeluxe]

Hello, i'm working on data structures and linked lists, and for the most part i am understanding these concepts. My question is, what exactly is the best way to describe this line of code - numbers* nums = getNewNumbers(); in my program? what exactly is it doing? I apologize in advance if this is a stupid question, sometimes simple things can elude me and drive me nuts, like this.

  #include <iostream>

using namespace std;

// structure with linked list
struct numbers
{
	int x;
	int y;
	int z;
	numbers *p_next_numbers;


};

numbers* getNewNumbers();
// getNewNumbers - gets new numbers from the linked list in the data structure that the pointer is pointing to
// @return numbers* - returns the fields in the linked list that the pointer is pointing to

void increment(numbers*);
// increment - function that will increment the fields with the giving numbers
// @param numbers* - pointer that points to the linked list that include the fields

int main()
{
	
	numbers* nums = getNewNumbers();

	// loop to show that the fields are being incremented by the giving
	// value each time
	for (int i = 0; i < 5; i++)
	{
		cout << nums->x << "\n";
		cout << nums->y << "\n";
		cout << nums->z << "\n";
		cout << nums->p_next_numbers << "\n\n";

		increment(nums);


		
	}

	cout << "\n\n";
	system("PAUSE");
	return 0;

}

numbers* getNewNumbers()
{
	numbers* p_nums = new numbers;
	
	p_nums->x = 1;
	p_nums->y = 5;
	p_nums->z = 10;
	p_nums->p_next_numbers = NULL;

	return p_nums;
}

void increment(numbers* p_nums)
{
	p_nums->x++;
	p_nums->y += 5;
	p_nums->z += 10;

}

[AbstractionAnon]

Line 52 declares a pointer p_nums, then allocates dynamic memory to hold one occurrence of the struct numbers and assigns the address of that memory to p_nums.

Line 54-57 initialize that structure.

Line 59 return the pointer to the dynamically allocated memory.

Line 27 declares a pointer to a struct of type numbers and initializes that pointer to the address return by getNewNumbers().

[MaseratiDeluxe]

Thank you! i was able to follow your logic and it made sense

[dhayden]

getNewNumbers() looks a lot like a constructor and increment() looks a lot like a method. Consider doing it like this insead:

#include <iostream>

using namespace std;

// structure with linked list
struct numbers
{
    numbers(int px, int py, int pz) {
	x = px;
	y = py;
	z = pz;
	p_next_numbers = NULL;
    }
    void increment() {
	x++;
	y += 5;
	z += 10;
    }

    int x;
    int y;
    int z;
    numbers *p_next_numbers;
};

int
main()
{

    numbers *nums = new numbers(1,5,10);

    // loop to show that the fields are being incremented by the giving
    // value each time
    for (int i = 0; i < 5; i++) {
	cout << nums->x << "\n";
	cout << nums->y << "\n";
	cout << nums->z << "\n";
	cout << nums->p_next_numbers << "\n\n";

	nums->increment();
    }

    cout << "\n\n";
    system("PAUSE");
    return 0;

}