xoj上的一道题目，要求输入一连串的四则运算表达式，然后求值，输入的运算数字范围是0-9999，结果在32整形之内。此程序用到了堆栈，涉及知识比较广-xoj on a subject, asked to enter a series of arithmetic expressions, and then find the value, enter the operation number in the range 0-9999, the results within 32 plastic. Th