I have this program that calculates the sum of the digits in a number but I have to make it recursive and i have no idea how a recursive function would even work for this kind of problem.
Where would I start?
Code:int digit = 0; int sum = 0; int number; printf("Enter a number:\n"); scanf("%d", &number); while(number != 0) { digit = number % 10; sum = sum + digit; number = number / 10; } printf("The sum of the digits is:\n%d", sum);
Recursion just needs to know when to stop. What tells your loop to stop? That's how you know to stop recusion. So, you are looking to pass it a number, and to stop when that number is zero. Since you are doing something with each number, you probably need to be returning something, and to be handling that something as well.
Quzah.
Hope is the first step on the road to disappointment.
Do you understand recursive functions at all? If not take a look here, and Google around for some more tutorials. Work some simpler examples (factorial is a classic).
Take a stab at it and post your code, and we'll help you (sorry, no free code here). To get you started, your loop condition (when to keep looping) is often the opposite of your base case (when to stop recursing). That is, if you keep looping while number is non-zero, than your base case should be number == 0. What comes after the base case should be similar to what's inside your loop.
Maybe something like:
Code:int recursive_func(int num) { int sum; assign last digit of num to sum if num has more than one digit pass all but the last digit of num to recursive_func() and add the return value to sum return sum }
If you understand what you're doing, you're not learning anything.
Well, there is also the matter that a recursive function calls itself.Originally Posted by quzah
I assumed that since he was being instructed to "make it recursive" that they told him what recursion was.
Quzah.
Hope is the first step on the road to disappointment.
I don't know much about recursive functions at all, but so far i have this. Is this anything close to what i should have?
Code:int sum(int x, int y) { if (number=0) { return 0; } else return (sum(sum, digit));
= is for assignment, == is for equality. Look at what everyone here has said so far. Pay attention to what itsme said.
Quzah.
Hope is the first step on the road to disappointment.
Which number are you referring to?
If you intend to test it's value you need == .. single = is for assignment
You're not summing anything. There should at least be a + sign somewhere in there. But yea, you're on the right track.
It's recursive but will not exactly do what you want it to do.Code:if(number=0) // don't. Instead do, if(number==0) //only if you want to compare
I don't care if someone doesn't like me, i was not put on earth to entertain everyone.
No King, no Queen, I am the ACE of battle.
You also have a problem here. You shouldn't be passing sum as a parameter to sum. sum is a function, you need to pass an integer for both parameters.
You have the right base case (assuming you switch = to == as many have already pointed out. Now, you need to use the body of your while loop as the "guts" of your recursion. There will be a little tweaking involved, but you're on the right track.
And do you still think that?
Lol :-)
Really?
If he/she was taught and he/she understood it well, then i think he/she shouldn't even write such a code. If he/she was told to call a function by itself, he/she should also be told about some ending condition. Ain't it?
I don't care if someone doesn't like me, i was not put on earth to entertain everyone.
No King, no Queen, I am the ACE of battle.
You need to learn to read.He didn't say he didn't understand recursion, or that he didn't know what recursion meant. He said he didn't know how to apply it to this problem. That's why I gave him the benefit of the doubt that he knew what it was. Besides, I already had answered the = and == issue before you two comedians showed up.but I have to make it recursive and i have no idea how a recursive function would even work for this kind of problem.
Learn to read. That goes for the OP too. You've already been hand fed the answer, and told that you've been hand fed the answer.
Quzah.
Hope is the first step on the road to disappointment.
