数据结构：带括号的算术表达式求值。能完成一位数的带括号的算术表达式的运算，结果可以为多位数。用栈实现中缀表达式和后缀表达式的转换。-data structure : the bracketed arithmetic expression is evaluated. Complete with a number of brackets arithmetic expression Operational results for the multi-digit number. With Stack Implementation grade expression and suffixes expression change.