I am unable to change array values through my function-CodePudding

What I am trying to do is to create a function that sorts an array given its length and a pointer to its head.

void Sort(int **arr, int len)
{
    int ech = 1;
    while (ech != 0)
    {
        ech = 0;
        for (int i = 0; i < len - 1; i  )
        {
            if (*(arr[i]) > *(arr[i   1]))
            {
                int temp = *(arr[i]);
                *(arr[i]) = *(arr[i   1]);
                *(arr[i   1]) = temp;
                ech  ;
            }
        }
    }
}

And when I try to call it in my main in returns a code=3221225477 error.

int main()
{
    int arr[10] = {100, 30, 100, 17, 11, 12, 7, 18, 200, 25};
    Sort(&arr, 10);
    // for (int i = 0; i < 10; i  )
    // {
    //     printf("%d ", arr[i]);
    // }

    return 0;
}

CodePudding user response：

When you look at the compiler warnings you see that you call Sort with an incompatible pointer. &arr is a pointer to array of int, but your Sort function wants a pointer to a pointer to int. It works if you change your Sort function to only take a pointer to int.

void Sort(int *arr, int len)
{
    int ech = 1;
    while (ech != 0)
    {
        ech = 0;
        for (int i = 0; i < len - 1; i  )
        {
            if ((arr[i]) > (arr[i   1]))
            {
                int temp = (arr[i]);
                (arr[i]) = (arr[i   1]);
                (arr[i   1]) = temp;
                ech  ;
            }
        }
    }
}

You call that function as Sort(arr, 10);.

CodePudding user response：

If you set your compiler to show all warnings, it will progressively walk you through a couple of levels of issues, the first masking the second...

The first indication there is a problem is the compiler warning against line Sort(&arr, 10); being called against your prototype void Sort(int **arr, int len):

warning: incompatible pointer types passing 'int (*)[10]' to parameter of type 'int **'

This should lead you to remove the address of operator &, (and subsequently to remove the extra * from void Sort(int **arr, int len) The next compile attempt should now indicate that you've exposed errors lurking in Sort() in the form of incorrect application of dereferences on the arr variables; *(arr[i]).

43, 17 error: indirection requires pointer operand ('int' invalid)
(repeats 5 times)

These are corrected by removing the dereference. i.e. change this: *(arr[i]): to thisarr[i]

Corrections to your code: (see comments)

void Sort(int *arr, int len)//change prototype
{
    int ech = 1;
    while (ech != 0)
    {
        ech = 0;
        for (int i = 0; i < len - 1; i  )
        {
            if (arr[i] > arr[i   1])
            {
                int temp = arr[i];//remove all defreferenceing of arr
                arr[i] = arr[i   1];
                arr[i   1] = temp;
                ech  ;
            }
        }
    }
}

int main(void)
{
    int arr[10] = {100, 30, 100, 17, 11, 12, 7, 18, 200, 25};
    Sort(arr, 10);//remove address of operator (arr is already a pointer)
    // for (int i = 0; i < 10; i  )
    // {
    //     printf("%d ", arr[i]);
    // }

    return 0;
}