Ruby没有评估就可以评估吗?
问题描述：
如何在不使用eval的情况下评估数学字符串?
How could I evaluate at mathematical string without using eval?
示例:
mathstring = "3+3"
是否可以在不使用评估的情况下进行评估?
Anyway that can be evaluated without using eval?
也许与正则表达式有关??
Maybe something with regex..?
答
您必须要么eval它，要么对其进行解析；而且由于您不想eval:
You must either or eval it, or parse it; and since you don't want to eval:
mathstring = '3+3'
i, op, j = mathstring.scan(/(\d+)([+\-*\/])(\d+)/)[0] #=> ["3", "+", "3"]
i.to_i.send op, j.to_i #=> 6
如果您想实现更复杂的内容，则可以使用RubyParser(如@LBg写道
If you want to implement more complex stuff you could use RubyParser (as @LBg wrote here - you could look at other answers too)