任意整数表达式求值程序，可运算加减乘除，负号要用括号括起-Any integer expression uation procedures, operations addition, subtraction, negative use brackets

使用键盘输入表达式，计算表达式的值并输出；将表达式转化成后缀表达式输出，利用后缀表达式求表达式的值并输出。-Keyboard input expression, the expression values calculated and output the expression into postfix expression output, the use of a postfix expression to uate the expression and output.