error C2440: '=' : cannot convert from 'void&n C语言

异常：error C2440: '=' : cannotconvert from 'void *' to 'struct _Grafo*' Conversion from 'void*' to pointer to non-'void' requires anexplicit cast

void Insert1(struct BTreeNode** BST, ElemType x)
{ if (*BST==NULL) //在为空指针的位置链接新结点

{ struct BTreeNode* p = malloc(sizeof(structBTreeNode));
p->data = x; p->left =p->right = NULL; *BST = p; }

这是个例子，只需要

struct BTreeNode* p = (structBTreeNode*)malloc(sizeof(struct BTreeNode));即可。