Fisher-Yates Shuffle?

[netodude]

Well, first off, this is homework for a c++ course. I just can't figure out how to get this fisher-yates shuffle to work without using arrays, as we haven't learned how to use those so I can't implement them.
Also, the instructor doesn't do a very good job of explaining things. He just reads off the textbook and isn't very helpful, to be honest. I've spoken to the rest of the class and we all feel this way.

The homework assignment is supposed to be the classic game of cows and bulls using the fisher-yates shuffle.

This is what I have for it:

void shuffle(vector<int> v)
{
    int n = v.size();
    for(int a=n-1; a>0; a--)
    {
        int j = randint(a, n);
        int tmp = v[a];
        v[a] = v[j];
        v[j] = tmp;
    }
}

I am a beginner, so I would appreciate any helps and tips. Thank you!

[Esslercuffi]

Well, it looks like you know how to use arrays to me. does the assignment specifically forbid using them?

It would seem ludicrous to not use an array for this, as the next best option I can think of involves using pointers. And if you haven't learned arrays yet, then you certainly haven't gotten into pointers.

[netodude]

No, not specifically, but we haven't gone over them in class at all so I'm assuming we aren't supposed to use them since its a beginner C++ class. Haven't learned pointers either, as you correctly assumed.

[Esslercuffi]

I'd go ahead and use the vector as you've done above then, to do this without arrays or pointers would require a large nasty convoluted set of nested if/else and/or switch blocks, all of which would be confusing and error prone. Arrays make it simple, direct, and sensible. I wouldn't think the instructor would penalize you for reading ahead in the book a bit.

[cire]

void shuffle(vector<int>& v) // Note the &

The code in the OP operates on a copy of the vector that is fed to it, so the original vector is unaffected and the changed vector stops existing at the end of the function.

[netodude]

Ah, so I was just missing the ampersand?
Tried speaking to the teacher, he said it should work even though I showed him the output being EXACTLY the same beforehand.
He did say no arrays when I asked, by the way.
He gave us

void shuffle(vector<int> v)

without it and had us fill in the rest so I never would've thought his code was missing something.
I had a feeling that I had to add something to apply the changes, but I didn't know what exactly. Thank you, I'll try it out when I get to a computer.

[netodude]

Haha that works! I swear, I spent so much time wondering why it wouldn't work, and it turns out all it was missing was the damn ampersand. Thanks a lot professor.
Thank you cire, much appreciated. You saved me countless hours of head-scratching! I'm glad I joined this forum!
He mentioned the ampersand once, but it was during a different lecture and he didn't even explain it. He just showed us code with the ampersand in a similar position and literally said don't worry about it, you don't need to know what it is yet. I'm really beginning to question the credibility of this instructor a lot more after this.

[Lowest0ne]

Well, at least your instructor is getting you right into the STL ( via vectors ).