[英]C Error: dereferencing pointer to incomplete type
So im getting a "Line 51: error: dereferencing pointer to incomplete type" when running this: 因此,在运行此代码时,我收到了“第51行:错误:将指针解引用为不完整类型”:
int main(void)
{
Tree * testTree;
testADT * data1;
testTree = createTree(compare,destroy);
data1 = malloc(sizeof(testADT));
data1->val = 10;
/* Line 51 */ addToTree(testTree,testTree->root,data1);
destroyBinTree(testTree);
return(0);
}
my addToTreeFunction: 我的addToTreeFunction:
TreeNode * addToTree(Tree * theTree,TreeNode * theTreeNode, TreeDataTypePtr data)
{
TreeNode * newNode;
if(isEmpty(theTree))
{
newNode = malloc(sizeof(TreeNode));
newNode->height = 0;
newNode->data = data;
theTree->root = newNode;
return theTree->root;
}else{
if(theTree->compare(theTreeNode->data,data) == 1) /* shows root data is smaller */
{
theTreeNode->right = addToTree(theTree,theTreeNode->right,data);
}else
if(theTree->compare(theTreeNode->data,data) == 0) /* shows root data is larger */
{
theTreeNode->left = addToTree(theTree,theTreeNode->left,data);
}
}
return theTreeNode;
}
my typedefs and structs: 我的typedef和结构:
struct tADT{
int val;
};
typedef struct tADT testADT;
typedef void * TreeDataTypePtr;
Could anyone provide some insight into whats going on? 任何人都可以对发生的事情提供一些见解吗? Thanks-in advance!
提前致谢!
Edit: This is in my module (.c) 编辑:这是在我的模块(.c)
struct AvlNode{
void * data;
struct AvlNode * left;
struct AvlNode * right;
int height;
};
struct AvlTree{
int (*compare) (TreeDataTypePtr data1, TreeDataTypePtr data2);
void (*destroy) (TreeDataTypePtr data);
struct AvlNode * root;
};
this is in the header (.h) 这是在标题(.h)中
struct AvlTreeNode;
struct AvlTree;
typedef struct AvlTree Tree;
typedef struct AvlNode TreeNode;
typedef void * TreeDataTypePtr;
Problem fixed by defining all structs/typedefs in header: 通过在标头中定义所有结构/类型定义来解决问题:
typedef struct AvlTree Tree;
typedef struct AvlNode TreeNode;
typedef void * TreeDataTypePtr;
struct AvlNode{
void * data;
struct AvlNode * left;
struct AvlNode * right;
int height;
};
struct AvlTree{
int (*compare) (TreeDataTypePtr data1, TreeDataTypePtr data2);
void (*destroy) (TreeDataTypePtr data);
struct AvlNode * root;
};
Are you defining "Tree" somewhere in one of your header files? 您要在其中一个头文件中的某个位置定义“树”吗? Can line 51 of the failing module see that header?
发生故障的模块的第51行可以看到该标头吗?
You must define "Tree" :) 您必须定义“树” :)
===================== ADDENDUM ==================== =====================附录===================
Thank you for updating your post with your "definition" of Tree: 感谢您使用“树”的“定义”更新您的帖子:
// .h file
struct AvlTreeNode;
struct AvlTree;
typedef struct AvlTree Tree;
...
But the fact remains - these are both "incomplete types". 但是事实仍然存在-它们都是“不完整的类型”。
You say you defined AvlTree and AvlTreeNode "in your module (.c)". 您说您在“模块(.c)”中定义了AvlTree和AvlTreeNode。
Q: Which .c translation unit? 问: 哪个 .c翻译单位?
Q: Is it defined in that translation unit before you try to use it? 问:在尝试使用翻译单元之前 ,它是否已在该翻译单元中定义?
Q: Is it used in any other translation unit? 问:它是否在其他翻译单位中使用?
Q: Why the duplicate/redundant/confusing typedef aliases? 问:为什么重复/冗余/混淆typedef别名?
Q: Why, for heaven's sake, don't you just define it in your .h file? 问:为什么,为了天堂,您不只是在.h文件中定义它吗?
testTree->root
取消引用testTree
,它是Tree
类型,未在任何地方定义。
The error suggests that you have a forward declaration of Tree
, but not a full definition of its corresponding structure. 该错误表明您具有
Tree
的前向声明,但没有其相应结构的完整定义。 That is why you can declare a pointer to Tree
, but you are not allowed to dereference its members. 这就是为什么您可以声明一个指向
Tree
的指针,但是不允许您取消引用其成员的原因。
Make sure that the compilation unit that contains main
has a #include
at the top for the header file that contains the definition of struct Tree
, this will fix this problem. 确保包含
main
的编译单元在包含struct Tree
定义的头文件的顶部具有#include
,这将解决此问题。
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