Question

I made a simple routine to sort an array witch accepts as a parameter an array of ints the problem is that when i compare the values array[i] shows the correct value in the debugger but array[i + 1] shows a bogus value … i guess is a pointer issue but i can’t figure it out what i am doing wrong.

Here is the code :

typedef int vector[10];

void task1(vector * param)
{
    bool ordered = false;
    while (!(ordered))
    {
        int tmp = 0;
        ordered = true;
        for (int i = 0; i < 9 ; i++)
        {
            if (*param[i] > *param[i+1])
            {
                tmp = *param[i];
                *param[i] = *param[i + 1];
                *param[i + 1] = tmp;
                ordered = false;
            }
        }
    }

}

int _tmain(int argc, _TCHAR* argv[])
{
    vector tavi = {10,88,77,192,7,27,82,1,882,13};

    task1(&tavi);
    for (int i = 0 ; i < 10 ; i ++)
        printf("%d ",tavi[i]);

    _getch();


    return 0;
}

Answer 1

The subscript-operator ([]) has a higher precedence than the derefence-operator (*), so *param[i] is actually *(param[i]). This means, you first go to the i-th element of param, and then dereference it – that is not what you want (param is not a pointer into an array). You want to dereference param and then go to the i-th element – this would be (*param)[i].