将中缀表达式转换为后缀表达式，并计算任意四则运算表达式的结果果，采用链表和队列实现，非文法和状态机，已通过测试。 -Infix convert an expression for the postfix expression, and calculate any four of expression is the result fruit, using linked lists and queues, non-grammar and state machines, has been test