广义表(C语言代码链式存储结构)

typedef enum
{
	ATOM,LIST
}Nodetype;//枚举类型
typedef struct GLnode
{
	Nodetype tag;//原子 或者 子表
	union {
		char atom;//字母
		struct
		{
			struct GLnode* head;
			struct GLndoe* tail;
		};
	};
}GLnode;
//创建原子结点
GLnode* createAtom(char data)
{
	GLnode* newnode = (GLnode*)malloc(sizeof(GLnode));
	if (newnode == NULL)
	{
		perror("error");
		exit(1);
	}
	newnode->tag = ATOM;
	newnode->atom = data;
	return newnode;
}
//创建子表结点
GLnode* createList(GLnode* head, GLnode* tail)
{
	GLnode* newnode = (GLnode*)malloc(sizeof(GLnode));
	if (newnode == NULL)
	{
		perror("error");
		exit(1);
	}
	newnode->tag = LIST;
	newnode->head = head;
	newnode->tail = tail;
	return newnode;
}
//打印广义表
void printNode(GLnode* node)
{
	if(node == NULL)
	{
		printf("()");
	}
	if (node->tag == ATOM)
	{
		printf("%c", node->atom);
	}
	else
	{
		printf("(");
		GLnode* pcur = node;
		while (pcur)
		{
			printNode(pcur->head);
			if (pcur->tail != NULL)
			{
				printf(",");
			}
			pcur = pcur->tail;
		}
		printf(")");
	}
}
int main()
{
	GLnode* atomA = createAtom('a');
	GLnode* atomB = createAtom('b');
	GLnode* atomC = createAtom('c');
	GLnode* atomD = createAtom('d');

	GLnode* suiblist = createList(atomA, createList(atomB, NULL));
	GLnode* list = createList(atomC, createList(suiblist,createList(atomD,NULL)));

	printNode(list);
	printf("\n");
	printNode(suiblist);

}