Recursion

[k1ll3rdr4g0n]

So I have this recursive function:

int test(int x, int y)
{
if (x==y)
return x;
else if (x > y)
return (x+y);
else
return test(x+1, y-1);
}

I tried to step through it...but I just can't wrap my brain around recursion, and when I run it....its only returning the y, such as for example, test(3, 9) it returns 8.

Why?

[dis1411]

the code as is should return 6... i suggest putting code to report the values of x and y at the top of the function

[penagate]

That's a bad subject for recursion; a loop would suffice.

You should only use recursion when variables change with each iteration. The only time I ever use it is when iterating through tree structures: here, it's the perfect solution. You could do this with a straight loop, but maintaining your position would be tedious. With recursion, you don't have to deal with that.

[k1ll3rdr4g0n]

the code as is should return 6... i suggest putting code to report the values of x and y at the top of the function

If I do that, it only reports x and y one time...really weird...
And I thought it was supposed to be 6 also...but my program says 8...
Hmmm....

[dis1411]

try

#include <iostream.h>

//using namespace std;

int test(int x, int y)
{
	cout << x << " " << y << endl;

	if (x==y)
		return x;
	else if (x > y)
		return (x+y);
	else
		return test(x+1, y-1);
}

void main()
{
	cout << test(3, 9) << endl;
}

[k1ll3rdr4g0n]

try

#include <iostream.h>

//using namespace std;

int test(int x, int y)
{
	cout << x << " " << y << endl;

	if (x==y)
		return x;
	else if (x > y)
		return (x+y);
	else
		return test(x+1, y-1);
}

void main()
{
	cout << test(3, 9) << endl;
}

Ahh yeah, me and my supervisor where I work helped me figure out my problem...I wasn't returning test(x +1, y-1) I was just calling it self again...

I hate recursion with a passion.

Btw, a few things wrong with your code, you commented out using namespace std, if you do that then you have to put std::cout instead of just cout. And you are using iostream.h which is old, it is suggested you use the new and highly improved 'iostream'.

[macmoy]

i agree!! u must include "using namespace std;"
(without using)= std::cout<<"hello";
(using)= cout<<"hello";