Thread: Pointer's address

That shouldn't even compile.

Depending on what deSerialize() actually does, it should be either

a) void deserialize(BstNode **root, FILE *fp);

or

b) void deserialize(BstNode *root, FILE *fp);


Looking at deSerialize(root->left, fp); I am guessing option (b), but without seeing the actual deSerialize implementation, *shrug*

Edit: now I'm not so sure about my guess because deSerialize() and deserialize() are different functions :/

Originally Posted by Hodor

That shouldn't even compile.

Depending on what deSerialize() actually does, it should be either

a) void deserialize(BstNode **root, FILE *fp);

or

b) void deserialize(BstNode *root, FILE *fp);


Looking at deSerialize(root->left, fp); I am guessing option (b), but without seeing the actual deSerialize implementation, *shrug*

Edit: now I'm not so sure about my guess because deSerialize() and deserialize() are different functions :/

Oh no they are not different functions the actual function is deSerialize I just changed it while typing here and forgot to change inside. Also program compiles and works as it should without a problem. I've just simply opened this topic to learn logic behind it. There is no problem with code. I can share rest of the code if you want but that is just irrelevant. There is only GetNewNode function there that you don't see which simply creates new BstNode struct, assigns val to its data then returns it.

Code:

BstNode* GetNewNode(int data) {
    BstNode* newNode = new BstNode();
    newNode->data = data;
    newNode->left = newNode->right = NULL;
    return newNode;
}

Also this is the struct:

Code:

struct BstNode {
    int data;
    BstNode* left;
    BstNode* right;
};

Originally Posted by Hodor

C code - 15 lines - codepad

Code:

#include <stdio.h>

struct BstNode {
    int data;
    BstNode* left;
    BstNode* right;
};

void deserialize(BstNode *&root, FILE *fp);

int main(void)
{
    printf("ok\n");
    return 0;
}

Output:
Line 5: error: expected specifier-qualifier-list before 'BstNode'
Line 9: error: expected ')' before '*' token

Somehow I don't think you're using C...

Oh damn... I opened topic to wrong place. It's not C, it is C++.

Edit: Although what makes it work at C++ but doesn't at C ?

Edit: Although what makes it work at C++ but doesn't at C ?

C doesn't have references in quite the same manner that C++ does.

Code:

void deserialize(BstNode *&root, FILE *fp);

That is a reference to a BstNode pointer.

@whiteflag

Can you explain that *& reference? And if I compile this as C file and change *& to ** as Hodor said would that work?

Can you explain that *& reference?

I thought I did. The variable root is a reference. The type of the reference is a BstNode pointer. I attempted to point this out using color coding before.

And if I compile this as C file and change *& to ** as Hodor said would that work?

Well, no. It would be a conscious effort to make that change, because you need to be consistent, and because pointers and references have different properties. In general, references cannot be reassigned once they are defined. They also do not need to be explicitly dereferenced, allocated, or released like pointers do.

Even if you made the change, new is not a C operator either.

So, changing from C++ to C is not really a good choice.

Originally Posted by whiteflags

Even if you made the change, new is not a C operator either.

Oops, I missed the new. But to be fair both of my comments were, really, based on the code give in the first post (apart from struct BstNode which I initially just used a made up struct -- before I saw the additional code)