Java Linked List implementation equivalent in C?

This is a discussion on Java Linked List implementation equivalent in C? within the C Programming forums, part of the General Programming Boards category; Firstly I do know how linked lists work and am a begginer in C but mildly competent. In the last ...

  1. #1
    Registered User
    Join Date
    Aug 2009
    Posts
    4

    Java Linked List implementation equivalent in C?

    Firstly I do know how linked lists work and am a begginer in C but mildly competent.

    In the last few lectures of term in my CompSci course the lecturer gave us some examples of Java classes and their equivalent C representations - his main example was a Hashset implementation and I am trying to replicate his approach with a linked list. The idea is to have the methods for the list embedded in the struct, so to add a new element one would do list->addToHead(list,item).

    I'm getting a lot of compile time errors with my code though, most of which I don't understand fully. My code is below

    PS - Yeah I know this is a trivial excercise, and not the best way to write C code, I'm just playing with this approach to try to get it to work!

    Code:

    Code:
    #include <stdlib.h>
    #include "bool.h"
    
    // Struct Definitions
    //=========================
    
    #define node_t struct _node_t
    node_t {
      // node contents
      void *item;
      node next, prev;
      
      // utility methods
      void (*insertBetween) (node THIS, node prev, node next);
      void (*remove) (node THIS);
      
    } *node;
    
    #define linkedList_t struct _linkedList_t
    linkedList_t {
      // list contents
      node head,tail;
      int size;
      
      // add to list methods
      void (*addToTail) (linkedList THIS, void *item);
      void (*addToHead) (linkedList THIS, void *item);
      void (*addAtIndex) (linkedList THIS, void *item, int index);
      
      // remove from list methods
      void (*removeByIndex) (linkedList THIS, int index);
      void (*removeByItem) (linkedList THIS, void *item);
      
      // utility methods
      int (*indexOf) (linkedList THIS, void *item);
      node (*nodeOf) (linkedList THIS, void *item)
      node (*nodeAtIndex) (linkedList THIS, int index);
      boolean (*contains) (linkedList THIS, void *item);
      boolean (*isEmpty) (linkedList THIS, void *item);
      
    } *linkedList;
    
    // Method Definitions
    //=========================
    
    // node constructor
    node newNode(void *item);
    
    // linked list constructor
    linkedList newLinkedList();
    
    // Method Implementations
    //=========================
    
    // INTERNAL NODE METHODS
    
      // insertion
      void insertBetween (node THIS, node prev, node next)
      {
        THIS->prev = prev;
        THIS->next = next;
        prev->next = THIS;
        next->prev = THIS;
      }
      void remove (node THIS)
      {
        THIS->prev->next = THIS->next;
        THIS->next->prev = THIS->prev;
        THIS->next = NULL;
        THIS->prev = NULL;
      }
      
    // INTERNAL LINKED LIST METHODS
    
      // add methods
      void addToTail (linkedList THIS, void *item)
      {
        node add = newNode(item);
        add->insertBetween(add, THIS->tail->prev, THIS->tail);
        THIS->size = THIS->size + 1;
      }
      void addToHead (linkedList THIS, void *item)
      {
        node add = newNode(item);
        add->insertBetween(add, THIS->head, THIS->head->next);
        THIS->size = THIS->size + 1;
      }
      void addAtIndex (linkedList THIS, void *item, int index)
      {
        if (index == 0)
          addToHead(THIS,item);
        else
        {
          node cur = nodeAtIndex(index-1);
          node add = newNode(item);
          add->insertBetween(add,cur,cur->next);
        }
      }
      
      // remove methods
      void removeByIndex (linkedList THIS, int index)
      {
        node cur = nodeAtIndex(index);
        cur->remove(cur);
        free(cur);
      }
      void removeByItem (linkedList THIS, void *item)
      {
        node cur = nodeOf(item);
        cur->remove(cur);
        free(cur);
      }
      
      // utility methods
      int indexOf(linkedList THIS, void *item)
      {
        int i=0;
        node cur=THIS->head->next;
        while (i < index && cur->item != item)
        {
          cur = cur->next;
          i++;
        }
        if (cur->item == item)
          return i;
        return -1;
      }
      node nodeOf(linkedList THIS, void *item)
      {
        int i=0;
        node cur=THIS->head->next;
        while (i < index && cur->item != item)
        {
          cur = cur->next;
          i++;
        }
        if (cur->item == item)
          return cur;
        return NULL;
      }
      node nodeAtIndex(linkedList THIS, int index)
      {
        if (index >= size)
          return NULL;
        int i=0;
        node cur=THIS->head->next;
        while (i < index)
        {
          cur = cur->next;
          i++;
        }
        return cur;
      }
      boolean contains(linkedList THIS, void *item)
      {
        return ( indexOf(THIS, item) != -1 );
      }
      boolean isEmpty(linkedList THIS)
      {
        return (head->next == tail);
      }
    
    // CONSTRUCTORS
    
      // node constructor
      node newNode(void *item)
      {
        // memory allocation
        node THIS = (node) (malloc( sizeof(node_t) ));
        
        // fields
        THIS->next = THIS;
        THIS->prev = THIS;
        THIS->item = THIS;
        
        // methods
        THIS->insertBetween = insertBetween;
        THIS->remove = remove;
        
        //return
        return THIS;
        
      }
      
      // list constructor
      linkedList newLinkedList()
      {
        // memory allocation
        linkedList THIS = (linkedList) (malloc( sizeof(linkedList_t) ));
        
        // fields
        THIS->head = newNode(NULL);
        THIS->tail = newNode(NULL);
          head->next = THIS->tail;
          tail->prev = THIS->head;
          
        // methods
          // add methods
          THIS->addToTail = addToTail;
          THIS->addToHead = addToHead;
          THIS->addAtIndex = addAtIndex;
          
          // remove methods
          THIS->removeByIndex = removeByIndex;
          THIS->removeByItem = removeByItem;
          
          // utility methods
          THIS->indexOf = indexOf;
          THIS->nodeOf = nodeOf;
          THIS->nodeAtIndex = nodeAtIndex;
          THIS->contains = contains;
          THIS->isEmpty = isEmpty;
          
        //return
        return THIS;
      }

    Errors:

    Code:
    lib/linkedlist.h:10: error: expected specifier-qualifier-list before ‘node’                                
    lib/linkedlist.h:21: error: expected specifier-qualifier-list before ‘node’
    lib/linkedlist.h:46: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘newNode’
    lib/linkedlist.h:49: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘newLinkedList’
    lib/linkedlist.h:57: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:64: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:75: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:81: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:87: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:100: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:106: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:114: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:127: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘nodeOf’
    lib/linkedlist.h:140: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘nodeAtIndex’
    lib/linkedlist.h:153: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:157: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:165: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘newNode’
    lib/linkedlist.h:185: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘newLinkedList’
    Any help is greatly appreciated!

  2. #2
    Registered User
    Join Date
    Jun 2009
    Posts
    452
    All except the first two errors are just missing semicolons and closing brackets, just go through and clean up your code and they will go away.

    Also, open question: can C structs contain function declarations? I thought that was OO only.

  3. #3
    Registered User
    Join Date
    Aug 2009
    Posts
    4
    Yes the first two errors are confusing, but ifyou look closely all the other errors after that aren't quite as simple as they appear to be. For example this error
    Code:
    lib/linkedlist.h:46: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘newNode’
    relates to this line:
    Code:
    node newNode(void *item);
    I have a feeling that if the first two errors were resolved, and the types node and linkedList were properly created (as I don't think they are being) all these other problems would go away too.

    In the examples we were given the structs did contain method definitions. I looked into this a bit and it is possible, the same way it is possible to pass functions by pointer. The structs simply contain pointers to functions.

    I should have mentioned - I gather that the first two errors occur normally if a name hasn't been specified before the struct is defined. E.g.

    Code:
    typedef struct { /*contents*/ } *node;
    instead of

    Code:
    typedef struct node_t { /*contents*/ } *node;
    But this is just from googling around, so I may be wrong.
    Last edited by pbtrn10k; 08-19-2009 at 07:45 AM. Reason: typo, extra info added

  4. #4
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    Location
    Singapore
    Posts
    21,885
    Quote Originally Posted by pbtrn10k
    I'm getting a lot of compile time errors with my code though, most of which I don't understand fully. My code is below
    Looking at your code, I get the impression that you want the identifier node to be a pointer to a node structure, which you name node_t. I suggest that you keep the pointer notation, and instead define:
    Code:
    typedef struct node node;
    
    struct node {
        /* node contents */
        void *item;
        node *next;
        node *prev;
    
        /* utility methods */
        void (*insertBetween)(node *this, node *prev, node *next);
        void (*remove)(node *this);
    };
    
    node *newNode(void *item);
    Notice that I changed the #define to a typedef, and that I no longer created a global pointer to a node structure (which was what you were doing previously).

    Quote Originally Posted by KBriggs
    Also, open question: can C structs contain function declarations? I thought that was OO only.
    Those are function pointer declarations. That said, pbtrn10k might be intending to simulate OO later, otherwise it seems to me that those declarations would not be useful.
    Last edited by laserlight; 08-19-2009 at 07:59 AM.
    C + C++ Compiler: MinGW port of GCC
    Version Control System: Bazaar

    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  5. #5
    Registered User
    Join Date
    Aug 2009
    Posts
    4
    I carried out the changes you suggested and although they do remove the first two errors I still get the other errors about missing ;, ) etc. They are still said to be missing in the middle of lines of code though.

    Here's the new code:
    Code:
    #include <stdlib.h>
    #include "bool.h"
    
    // Struct Definitions
    //=========================
    
    typedef struct node node
    {
      // node *contents
      void *item;
      node *next, *prev;
      
      // utility methods
      void (*insertBetween) (node *THIS, node *prev, node *next);
      void (*remove) (node *THIS);
      
    };
    
    typedef struct linkedList linkedList
    {
      // list contents
      node *head, *tail;
      int size;
      
      // add to list methods
      void (*addToTail) (linkedList *THIS, void *item);
      void (*addToHead) (linkedList *THIS, void *item);
      void (*addAtIndex) (linkedList *THIS, void *item, int index);
      
      // remove from list methods
      void (*removeByIndex) (linkedList *THIS, int index);
      void (*removeByItem) (linkedList *THIS, void *item);
      
      // utility methods
      int (*indexOf) (linkedList *THIS, void *item);
      node* (*nodeOf) (linkedList *THIS, void *item)
      node* (*nodeAtIndex) (linkedList *THIS, int index);
      boolean (*contains) (linkedList *THIS, void *item);
      boolean (*isEmpty) (linkedList *THIS, void *item);
      
    };
    
    // Method Definitions
    //=========================
    
    // node *constructor
    node* newNode(void *item);
    
    // linked list constructor
    linkedList* newLinkedList();
    
    // Method Implementations
    //=========================
    
    // INTERNAL NODE METHODS
    
      // insertion
      void insertBetween (node *THIS, node *prev, node *next)
      {
        THIS->prev = prev;
        THIS->next = next;
        prev->next = THIS;
        next->prev = THIS;
      }
      void remove (node *THIS)
      {
        THIS->prev->next = THIS->next;
        THIS->next->prev = THIS->prev;
        THIS->next = NULL;
        THIS->prev = NULL;
      }
      
    // INTERNAL LINKED LIST METHODS
    
      // add methods
      void addToTail (linkedList *THIS, void *item)
      {
        node *add = newNode(item);
        add->insertBetween(add, THIS->tail->prev, THIS->tail);
        THIS->size = THIS->size + 1;
      }
      void addToHead (linkedList *THIS, void *item)
      {
        node *add = newNode(item);
        add->insertBetween(add, THIS->head, THIS->head->next);
        THIS->size = THIS->size + 1;
      }
      void addAtIndex (linkedList *THIS, void *item, int index)
      {
        if (index == 0)
          addToHead(THIS,item);
        else
        {
          node *cur = nodeAtIndex(index-1);
          node *add = newNode(item);
          add->insertBetween(add,cur,cur->next);
        }
      }
      
      // remove methods
      void removeByIndex (linkedList *THIS, int index)
      {
        node *cur = nodeAtIndex(index);
        cur->remove(cur);
        free(cur);
      }
      void removeByItem (linkedList *THIS, void *item)
      {
        node *cur = nodeOf(item);
        cur->remove(cur);
        free(cur);
      }
      
      // utility methods
      int indexOf(linkedList *THIS, void *item)
      {
        int i=0;
        node *cur=THIS->head->next;
        while (i < index && cur->item != item)
        {
          cur = cur->next;
          i++;
        }
        if (cur->item == item)
          return i;
        return -1;
      }
      node* nodeOf(linkedList *THIS, void *item)
      {
        int i=0;
        node *cur=THIS->head->next;
        while (i < index && cur->item != item)
        {
          cur = cur->next;
          i++;
        }
        if (cur->item == item)
          return cur;
        return NULL;
      }
      node* nodeAtIndex(linkedList *THIS, int index)
      {
        if (index >= size)
          return NULL;
        int i=0;
        node *cur=THIS->head->next;
        while (i < index)
        {
          cur = cur->next;
          i++;
        }
        return cur;
      }
      boolean contains(linkedList *THIS, void *item)
      {
        return ( indexOf(THIS, item) != -1 );
      }
      boolean isEmpty(linkedList THIS)
      {
        return (head->next == tail);
      }
    
    // CONSTRUCTORS
    
      // node *constructor
      node* newNode(void *item)
      {
        // memory allocation
        node *THIS = (node) (malloc( sizeof(node_t) ));
        
        // fields
        THIS->next = THIS;
        THIS->prev = THIS;
        THIS->item = THIS;
        
        // methods
        THIS->insertBetween = insertBetween;
        THIS->remove = remove;
        
        //return
        return THIS;
        
      }
      
      // list constructor
      linkedList* newLinkedList()
      {
        // memory allocation
        linkedList *THIS = (linkedList) (malloc( sizeof(linkedList_t) ));
        
        // fields
        THIS->head = newNode(NULL);
        THIS->tail = newNode(NULL);
          head->next = THIS->tail;
          tail->prev = THIS->head;
          
        // methods
          // add methods
          THIS->addToTail = addToTail;
          THIS->addToHead = addToHead;
          THIS->addAtIndex = addAtIndex;
          
          // remove methods
          THIS->removeByIndex = removeByIndex;
          THIS->removeByItem = removeByItem;
          
          // utility methods
          THIS->indexOf = indexOf;
          THIS->nodeOf = nodeOf;
          THIS->nodeAtIndex = nodeAtIndex;
          THIS->contains = contains;
          THIS->isEmpty = isEmpty;
          
        //return
        return THIS;
      }
    And here's the new errors:
    Code:
    lib/linkedlist.h:8: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{’ token               
    lib/linkedlist.h:20: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘{’ token              
    lib/linkedlist.h:47: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
    lib/linkedlist.h:50: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
    lib/linkedlist.h:58: error: expected ‘)’ before ‘*’ token
    lib/linkedlist.h:65: error: expected ‘)’ before ‘*’ token
    lib/linkedlist.h:76: error: expected ‘)’ before ‘*’ token
    lib/linkedlist.h:82: error: expected ‘)’ before ‘*’ token
    lib/linkedlist.h:88: error: expected ‘)’ before ‘*’ token
    lib/linkedlist.h:101: error: expected ‘)’ before ‘*’ token
    lib/linkedlist.h:107: error: expected ‘)’ before ‘*’ token
    lib/linkedlist.h:115: error: expected ‘)’ before ‘*’ token
    lib/linkedlist.h:128: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
    lib/linkedlist.h:141: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
    lib/linkedlist.h:154: error: expected ‘)’ before ‘*’ token
    lib/linkedlist.h:158: error: expected ‘)’ before ‘THIS’
    lib/linkedlist.h:166: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
    lib/linkedlist.h:186: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘*’ token
    Quote Originally Posted by laserlight View Post
    Those are function pointer declarations. That said, pbtrn10k might be intending to simulate OO later, otherwise it seems to me that those declarations would not be useful.
    The object of the lectures in question was to show how OO can be simulated in a non-OO language like C. That said, I'm doing this to learn and because our lecturer has a reputation for putting code in his handouts which doesn't compile, so I want to see if he was actually telling the truth!!

  6. #6
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    Location
    Singapore
    Posts
    21,885
    Quote Originally Posted by pbtrn10k
    I carried out the changes you suggested and although they do remove the first two errors I still get the other errors about missing ;, ) etc. They are still said to be missing in the middle of lines of code though.
    Notice that in my example the typedef comes before and is separate from the struct definition.
    C + C++ Compiler: MinGW port of GCC
    Version Control System: Bazaar

    Look up a C++ Reference and learn How To Ask Questions The Smart Way

  7. #7
    Registered User
    Join Date
    Aug 2009
    Posts
    4
    Fantastic! There were also some other problems in the code which I got ironed out. Here's the final version:

    Code:
    #include <stdlib.h>
    #include "bool.h"
    
    // Struct Definitions
    //=========================
    
    typedef struct node node;
    
    struct node {
      // node *contents
      void *item;
      node *next, *prev;
      
      // utility methods
      void (*insertBetween) (node *THIS, node *prev, node *next);
      void (*removeFromList) (node *THIS);
      
    };
    
    typedef struct linkedList linkedList;
    
    struct linkedList {
      // list contents
      node *head, *tail;
      int size;
      
      // add to list methods
      void (*addToTail) (linkedList *THIS, void *item);
      void (*addToHead) (linkedList *THIS, void *item);
      void (*addAtIndex) (linkedList *THIS, void *item, int index);
      
      // remove from list methods
      void (*removeByIndex) (linkedList *THIS, int index);
      void (*removeByItem) (linkedList *THIS, void *item);
      
      // utility methods
      int (*indexOf) (linkedList *THIS, void *item);
      node* (*nodeOf) (linkedList *THIS, void *item);
      node* (*nodeAtIndex) (linkedList *THIS, int index);
      boolean (*contains) (linkedList *THIS, void *item);
      boolean (*isEmpty) (linkedList *THIS);
      
    };
    
    // Method Definitions
    //=========================
    
    // node *constructor
    node* newNode(void *item);
    
    // linked list constructor
    linkedList* newLinkedList();
    
    // node methods
    void insertBetween(node *THIS, node *prev, node *next);
    void removeFromList(node *THIS);
      
    // list methods
    void addToTail(linkedList *THIS, void *item);
    void addToHead(linkedList *THIS, void *item);
    void addAtIndex(linkedList *THIS, void *item, int index);
    void removeFromListByIndex(linkedList *THIS, int index);
    void removeFromListByItem(linkedList *THIS, void *item);
    int indexOf(linkedList *THIS, void *item);
    node* nodeOf(linkedList *THIS, void *item);
    node* nodeAtIndex(linkedList *THIS, int index);
    boolean contains(linkedList *THIS, void *item);
    boolean isEmpty(linkedList *THIS);
    
    // Method Implementations
    //=========================
    
    // INTERNAL NODE METHODS
    
      // insertion
      void insertBetween (node *THIS, node *prev, node *next)
      {
        THIS->prev = prev;
        THIS->next = next;
        prev->next = THIS;
        next->prev = THIS;
      }
      void removeFromList (node *THIS)
      {
        THIS->prev->next = THIS->next;
        THIS->next->prev = THIS->prev;
        THIS->next = NULL;
        THIS->prev = NULL;
      }
      
    // INTERNAL LINKED LIST METHODS
    
      // add methods
      void addToTail (linkedList *THIS, void *item)
      {
        node *add = newNode(item);
        add->insertBetween(add, THIS->tail->prev, THIS->tail);
        THIS->size = THIS->size + 1;
      }
      void addToHead (linkedList *THIS, void *item)
      {
        node *add = newNode(item);
        add->insertBetween(add, THIS->head, THIS->head->next);
        THIS->size = THIS->size + 1;
      }
      void addAtIndex (linkedList *THIS, void *item, int index)
      {
        if (index == 0)
          addToHead(THIS,item);
        else
        {
          node *cur = nodeAtIndex(THIS, index-1);
          node *add = newNode(item);
          add->insertBetween(add,cur,cur->next);
        }
      }
      
      // removeFromList methods
      void removeByIndex (linkedList *THIS, int index)
      {
        node *cur = nodeAtIndex(THIS, index);
        cur->removeFromList(cur);
        free(cur);
      }
      void removeByItem (linkedList *THIS, void *item)
      {
        node *cur = nodeOf(THIS, item);
        cur->removeFromList(cur);
        free(cur);
      }
      
      // utility methods
      int indexOf(linkedList *THIS, void *item)
      {
        int i=0;
        node *cur=THIS->head->next;
        while (i < THIS->size && cur->item != item)
        {
          cur = cur->next;
          i++;
        }
        if (cur->item == item)
          return i;
        return -1;
      }
      node* nodeOf(linkedList *THIS, void *item)
      {
        int i=0;
        node *cur=THIS->head->next;
        while (i < THIS->size && cur->item != item)
        {
          cur = cur->next;
          i++;
        }
        if (cur->item == item)
          return cur;
        return NULL;
      }
      node* nodeAtIndex(linkedList *THIS, int index)
      {
        if (index >= THIS->size)
          return NULL;
        int i=0;
        node *cur=THIS->head->next;
        while (i < index)
        {
          cur = cur->next;
          i++;
        }
        return cur;
      }
      boolean contains(linkedList *THIS, void *item)
      {
        return ( indexOf(THIS, item) != -1 );
      }
      boolean isEmpty(linkedList *THIS)
      {
        return (THIS->head->next == THIS->tail);
      }
    
    // CONSTRUCTORS
    
      // node *constructor
      node* newNode(void *item)
      {
        // memory allocation
        node *THIS = (node *) (malloc( sizeof(node) ));
        
        // fields
        THIS->next = THIS;
        THIS->prev = THIS;
        THIS->item = THIS;
        
        // methods
        THIS->insertBetween = insertBetween;
        THIS->removeFromList = removeFromList;
        
        //return
        return THIS;
        
      }
      
      // list constructor
      linkedList* newLinkedList()
      {
        // memory allocation
        linkedList *THIS = (linkedList *) (malloc( sizeof(linkedList) ));
        
        // fields
        THIS->head = newNode(NULL);
        THIS->tail = newNode(NULL);
          THIS->head->next = THIS->tail;
          THIS->tail->prev = THIS->head;
          
        // methods
          // add methods
          THIS->addToTail = addToTail;
          THIS->addToHead = addToHead;
          THIS->addAtIndex = addAtIndex;
          
          // remove methods
          THIS->removeByIndex = removeByIndex;
          THIS->removeByItem = removeByItem;
          
          // utility methods
          THIS->indexOf = indexOf;
          THIS->nodeOf = nodeOf;
          THIS->nodeAtIndex = nodeAtIndex;
          THIS->contains = contains;
          THIS->isEmpty = isEmpty;
          
        //return
        return THIS;
      }
    I only have one question left - why does your suggestion work?!

  8. #8
    and the Hat of Guessing tabstop's Avatar
    Join Date
    Nov 2007
    Posts
    14,185
    What -- putting the typedef elsewhere? Typedef creates a name -- but it doesn't create the name until the statement is finished. So
    Code:
    typedef struct node {
        int bob; //typedef not yet done
        struct node *next; //have to use the "real" name since the typedef not yet done
    } node; //NOW we can use node

  9. #9
    C++ Witch laserlight's Avatar
    Join Date
    Oct 2003
    Location
    Singapore
    Posts
    21,885
    Quote Originally Posted by pbtrn10k
    I only have one question left - why does your suggestion work?!
    Your first try did not work because you were declaring node as a pointer to a struct _node_t. Your next try did not work because of a syntax error: you were placing the typedef name before the struct definition was complete. My suggestion works because it first declares node as an alias for struct node, and then defines struct node. Since node has been declared, you can use the name node within the definition of struct node. If not, you would have to go with tabstop's suggestion.
    C + C++ Compiler: MinGW port of GCC
    Version Control System: Bazaar

    Look up a C++ Reference and learn How To Ask Questions The Smart Way

Popular pages Recent additions subscribe to a feed

Similar Threads

  1. C++ Linked list program need help !!!
    By dcoll025 in forum C++ Programming
    Replies: 1
    Last Post: 04-20-2009, 10:03 AM
  2. Pleas take a look & give a critique
    By sh3rpa in forum C++ Programming
    Replies: 14
    Last Post: 10-19-2007, 10:01 PM
  3. Anyone good with linked list.....I am not....
    By chadsxe in forum C++ Programming
    Replies: 11
    Last Post: 11-10-2005, 01:48 PM
  4. How can I traverse a huffman tree
    By carrja99 in forum C++ Programming
    Replies: 3
    Last Post: 04-28-2003, 05:46 PM
  5. singly linked list
    By clarinetster in forum C Programming
    Replies: 2
    Last Post: 08-26-2001, 10:21 PM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21