Thread: why i get this error..

  1. #1
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    why i get this error..

    in the end i want elt to point on some address
    why i get
    c(28) : error C2223: left of '->next' must point to struct/union
    but when i change it to
    Code:
    (*p)->next->next;
    it works fine,why i need these cols
    Code:
    #include <stdio.h>
    #include <stdlib.h>
    typedef struct node {
        int value;
        struct node *next;
    }Node;
    
    void what1(Node ** p,int num);
    int main()
    {
       Node *p;
       p=(Node *)malloc(sizeof(Node));
       p->value=1;
       p->next=(Node *)malloc(sizeof(Node));
       p->next->value=2;
       what1(&p,0);
       free(p);
        return 0;
    }
    
    void what1(Node ** p,int num)
    {
       Node *elt;
       elt=(Node*)malloc(sizeof(Node));
       elt->next=*p;
       elt->value=num;
        *p=elt;
    	elt=*p->next->next;
    }
    Last edited by transgalactic2; 03-21-2009 at 02:54 PM.

  2. #2
    and the Hat of Guessing tabstop's Avatar
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    Because, as the error message pointed out, p does not point to a struct or a union. It points to a pointer.

  3. #3
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    Why do you think you need the dereferencing operator "*" in the first place?

  4. #4
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    so why the cols makes it wright?
    works:
    elt=(*p)->next->next;


    doesnt work

    elt=*p->next->next;

  5. #5
    Hurry Slowly vart's Avatar
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    All problems in computer science can be solved by another level of indirection,
    except for the problem of too many layers of indirection.
    David J. Wheeler

  6. #6
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    Quote Originally Posted by transgalactic2 View Post
    so why the cols makes it wright?
    works:
    elt=(*p)->next->next;


    doesnt work

    elt=*p->next->next;
    read about operator precedence and binding first!

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