算数表达式求解问题。模拟计算机内部算数表达式的计算过程，用顺序结构的栈实现存储，可以从键盘输入一个算数表达式，并可以判断表达式是否合法，输出正确的结果，并显示输入序列和栈的变化过程。-Problem of solving arithmetic expressions. Arithmetic expression inside the computer simulation calculation, the structure of the stack with the order to achieve storage, you can enter an arithmetic expression from the keyboard, and can determine the legality of an expression and output the correct results and displays the input sequence and stack the change process.