队列是一种特殊的线性表，特殊之处在于它只允许在表的前端（front）进行删除操作，而在表的后端（rear）进行插入操作，和栈一样，队列是一种操作受限制的线性表。进行插入操作的端称为队尾，进行删除操作的端称为队头。(The queue is a special linear list, and the special thing is that it only allows the deletion of the front end of the table (front), and the insertion operation at the back end of the table (rear), just like the stack, the queue is a restricted linear list. The end of the insertion operation is called the queue tail, and the end of the deletion operation is called the header.)