这是我在大学波尔多1类PROJET。我professieur Mr.Baudon创世这些代码给Java结构hashtree的例子。这是评估一个数值表达式，实现了类计算器。-This is to achieve a class calculator evaluating a numeric expression.

Prefixed expressions are used to facilitate analysis:



　　 no priority

　　 no associativity

　　 the battery is required to calculate the recursive calls



For example,+/4 2 1 the result is 3 (= 4/2+ 1)

On the other hand, the character　-　being used as a sign by StreamTokenizer, the corresponding binary operator will be represented by the word "less".