表达式求值：给定一个浮点数混合运算的中缀表达式，分别实现：转换成为后缀表达式，然后求值；直接对中缀表达式求值两种求值算法两种实现方法。表达式中包含的运算符：加法+，减法-，乘法*，除法/，括号()，乘方#等运算符。运算符的优先级和结合性符合数学运算法则。比如：命令行输入 (-2.0)+(1.0+2.0)*3.0-2.0#2.0回车

(1)中缀表达式输出：

(-2.0)+ (1.0+2.0)*3.0-2.0#2.0=3.0

(2)后缀表达式输出:

-2.0 1.0 2.0 + 3.0 * + 2.0 2.0 # -

(-2.0)+ (1.0+2.0)*3.0-2.0#2.0=3.0-Expression evaluation: in infix expression to a floating point number to the mix operator, respectively, to achieve: convert postfix expression and then evaluated　infix expression evaluation are two evaluation algorithms implemented in two methods. The expression contains operators: addition+, subtraction-, multiplication*, division /, parentheses (), involution#, and other operators. Operator precedence and associativity of the mathematical algorithm. For example: the command-line input (-2.0)+ (1.0+2.0)* 3.0-2.0# 2.0 Enter

(1) infix expression output:

(-2.0)+ (1.0+2.0)* 3.0-2.0# 2.0 = 3.0

(2) postfix expression output:

-2.0 1.0 2.0+ 3.0*+ 2.0 2.0-

(-2.0)+ (1.0+2.0)* 3.0-2.0# 2.0 = 3.0