typedef struct Node *PtrToNode;
struct Node { /* 队列中的结点 */ ElementType Data; PtrToNode Next; };
typedef PtrToNode Position; struct QNode
{ Position Front, Rear; /* 队列的头、尾指针 */
int MaxSize; /* 队列最大容量 */ };
typedef struct QNode *Queue; bool IsEmpty( Queue Q )
{ return ( Q->Front == NULL); } ElementType DeleteQ( Queue Q )
{ Position FrontCell; ElementType FrontElem; if ( IsEmpty(Q) )
{ printf("队列空");
return ERROR; }
else { FrontCell = Q->Front;
if ( Q->Front == Q->Rear ) /* 若队列只有一个元素 */
Q->Front = Q->Rear = NULL; /* 删除后队列置为空 */
else
Q->Front = Q->Front->Next;
FrontElem = FrontCell->Data; free( FrontCell ); /* 释放被删除结点空间 */
return FrontElem; } }