Recursion.

[xcrossmyheartx]

The goal of the program that I have to create is to have the user enter a number. From there, a function will countdown from that number to 0 and then return0;

The only hint that my instructor gave us was to lookup "recursion" on the internet. I am sorta confused about that.

Also, we ARE NOT allowed to use loops.

Here's the base code, I need to edit only the function.

#include <iostream>

using namespace std;

void countDown(int x)
{

}

int main()

{

	int num;
	cout << "Enter a positive number: ";
	cin >> num;
	countDown(num);
}

Any ideas?

[Athar]

Any ideas?

Yup... look up recursion.

[PiMaster]

Recursion is executing a function from inside the same function. For example:

int factorial(int num){
	num*=num-1;
	--num;
	if(num!=1){
		factorial(num);}
	return num;}

The above code would find the factorial of "num" by calling "factorial" inside itself until the number is 1.

[xcrossmyheartx]

Okay, that made sense. I'm able to make my function. This might seem like a stupid question, but I can't stop my program from putting a 0 (the assignment asks to not display the zero and to just show the return 0; screen)

I tried putting in the return 0; function, but my program had an error that said void can't return anything.

Here's my code:

#include <iostream>

using namespace std;

void countDown(int x)
{
	cout << x << " ";
	if (x > 0)
	{
		countDown(x - 1);
	}
	
}


int main()

{

	int num;
	cout << "Enter a positive number: ";
	cin >> num;
	countDown(num);
}

[PiMaster]

You just need to change "x > 0" to "x > 1" (line 8). Otherwise, when x==1, it'll recurse with x-1, which is 0.

Also, void functions aren't supposed to return anything - if you need to exit a void function, you just type "return;".

[xcrossmyheartx]

Gotcha! Thanks so much for the help guys :)