結構和鏈表（C）

Question

我試圖實現鏈接列表來保存歷史信息。

我的節點結構的定義如下：

struct HistoryNode { 
    int Value; 
    struct HistoryNode *Last, *Next; 
}; 

我還創造了另一個結構，包含指向頭/尾/列表中的當前節點：

struct _History { 
    struct HistoryNode *Head, *Tail, *Current; 
} History = { 
    NULL, NULL, NULL, 
}; 

最後，我創建了一個函數，將一個節點添加到列表中：

void AddHistory(void) { 
    struct HistoryNode *NewNode; 

    //Allocate new node memory 
    NewNode = malloc(sizeof(NewNode)); 
    if(NewNode == NULL) { 
     Die("malloc(%d) failed", sizeof(NewNode)); 
    } 

    //Re-arrange pointers in new node and head/tail/current 
    if(History.Current == NULL) { 
     NewNode->Next = NULL; 
     NewNode->Last = NULL; 

     History.Current = NewNode; 
     History.Head = NewNode; 
     History.Tail = NewNode; 
    } else { 
     NewNode->Next = NULL; 
     NewNode->Last = History.Current; 

     History.Current = NewNode; 
     History.Tail = NewNode; 
    } 
} 

GCC吐出這個回來ou t以及幾個錯誤：

Scribe.c: In function 'AddHistory': 
Scribe.c:509:15: error: request for member 'Current' in something not a structure or union 
Scribe.c:513:16: error: request for member 'Current' in something not a structure or union 
Scribe.c:514:16: error: request for member 'Head' in something not a structure or union 
Scribe.c:515:16: error: request for member 'Tail' in something not a structure or union 
Scribe.c:518:32: error: request for member 'Current' in something not a structure or union 
Scribe.c:520:16: error: request for member 'Current' in something not a structure or union 
Scribe.c:521:16: error: request for member 'Tail' in something not a structure or union 

我不知道爲什麼會發生這種情況，有什麼幫助？

謝謝， - 亞歷

Answer 1

如果將History聲明爲全局變量，則編譯成功，如http://cfiddle.net/LwucyB中所示。對這個問題，還應注意有關的NewNode分配應該是如下

NewNode = malloc(sizeof(struct HistoryNode)); 

您需要分配的結構，而不是隻是空間的指針。

Answer 2

你想對malloc的sizeof（HistoryNode），不NewNode（這是一個指向HistoryNode）。