输入一个表达式，其中包含0~9及负号小数点组成的浮点数和加减乘除运算符，还应该包含括号。其他字符非法的输入均报错,表达式以#结束。输出运算结果。程序所能达到的结果有：适用于浮点型的计算，且适用于多位数的运算，适用于负数的运算。对输入的表达式有判断对错的功能-Input a expressions, including 0 ~ 9 and minus the decimal point of floating-point and add, subtract, multiply and divide operator, should also contains parentheses. Other characters are illegal input error, and expression to# end. Output operation result. Program can achieve results are: applicable to the calculation of floating point type, and is applicable to the operations of connection, and is suitable for the operation of a negative number. The input expression is the function of the judge