why does this function keep crashing?

Question

Forethought: If it is needed then I can add the class definition. Problem: I get a STATUS_ACCESS_VIOLATION whenever I try to run this function in my program. I was wondering what was going on. Am I out of bounds somewhere? If I could reason it out myself I would. But I cannot figure it out alone. I'm very close to just hiring someone to do the debugging for me. It's worth my wile. So anyway, this needs to be looked over and given a little TLC. Thanks in advance!

int S_Rend::count(bitset<8> alpha, bitset<8> spec) {

    int bn;
    vector< bitset<8> > cnt;
    bitset<8> curr;
    int chmp;

    eta = (alpha & spec);
    theta = (alpha | spec);

    cnt[0] = eta & alpha;
    cnt[1] = eta | alpha;
    cnt[2] = eta & spec;
    cnt[3] = eta | spec;
    cnt[4] = theta & alpha;
    cnt[5] = theta | alpha;
    cnt[6] = theta & spec;
    cnt[7] = theta | spec;
    cnt[8] = cnt[0] & cnt[5];
    cnt[9] = cnt[6] | cnt[1];
    cnt[10] = cnt[2] & cnt[7];
    cnt[11] = cnt[4] | cnt[3];

    for (int i=0;i<11;i++)
        for (int j=i;j<=11;j++) {
            curr = cnt[i];
            if (cnt[j] == curr)
                bn++;
            if (bn>chmp)
                chmp=bn;
        }

    return chmp;
}

int S_Rend::s_render(ifstream& in, ofstream& out) {

    int i, n;
    int t;
    int chk;
    in >> lambda;
    in >> size;
    in >> delta;
    in >> chk;
    t=(int&)beta;
    int bn=0;

    while (size-1>=bn) {
        t=s_nop((int&)t,0);
        cred.push_back(t);
        bn++;       
    }

    if (cred[bn-1]==chk)
        cout << "\nValidity Pass... Success!" << endl;
    else {
        printf("\nValidity Pass...Fail! %u != %u",cred[cred.size()-1],chk);
        return 1;
    }

    cout << "\nWriting to Buffer..." << endl;
    i=0;
    spec = lambda;
int f;
while (bn-1>=0) {
    alpha = (int&)cred[bn-1];
    f=count(alpha, spec);
    eta = (int&)f;
    spec ^= alpha ^ eta;
    btrace.push_back(f);
    cout << f << " ";
    bn--;
}

    cout << "One more second..\n";

    while (i<=bn-1) {
        delta = (int&)btrace[bn];
        out << (const char)(int&)delta;
        i++;
    }

    cout << "\nBuffer Written... Exiting..\n";
    in.close();
    out.close();
    printf("*");
    return 0;
}

Answer 1

At this point : while (bn) { alpha = (int&)cred[bn]; f=count(alpha, spec);

bn == size and size == cred.size() so you read ouside the vector. Assuming cred is empty at start

Answer 2

The most glaring issue is that you're writing (and reading) from a vector with out-of-bounds indices:

int S_Rend::count(bitset<8> alpha, bitset<8> spec) 
{
    int bn;
    vector< bitset<8> > cnt;
    bitset<8> curr;
    int chmp;

    eta = (alpha & spec);
    theta = (alpha | spec);

    cnt[0] = eta & alpha;  // <-- Illegal access
    ...
}

Well, we can stop right there.

The std::vector is not sized, so it cannot hold any elements. The last line assumes that vector can hold at least one item (item 0). Thus this is undefined behavior.

Size the vector appropriately before accessing elements by calling push_back, vector::resize, vector::insert, vector::emplace_back, or construct the vector by issuing one of the constructors that sizes the vector in addition to constructing it.

std::vector description

Since it seems you want 12 items, then you can construct it with 12 items.

int S_Rend::count(bitset<8> alpha, bitset<8> spec) 
{
    int bn;
    vector< bitset<8> > cnt(12);
    bitset<8> curr;
    int chmp;

    eta = (alpha & spec);
    theta = (alpha | spec);

    cnt[0] = eta & alpha;  // <-- ok
    ...
}

Also, as a debugging aid, you could have used std::vector::at instead of operator [ ] to access the vector items. Using at() would have immediately thrown a std::out_of_bounds exception indicating that you were accessing the vector with an invalid index (instead of the program continuing as if nothing is wrong).

---

The second thing that seems dubious is you casting a std::bitset to an int reference, or vice-versa. As you observed, without the cast, you get an error. Using a C-style cast to "shut the compiler up" is not a good idea, as all you're doing is bypassing the type-safety mechanism that C++ has in place at compile-time.

If the compiler says to you "this shouldn't be done", and then you override it by issuing a C-style cast, prepare to suffer the consequences if / when your program shows erratic behavior.

To properly convert between a std::bitset and an int, there are methods for this, namely std::to_ulong.

How to convert from bitset to an int