如何在Ruby中编写switch语句 [英] How to write a switch statement in Ruby

问题描述

如何在Ruby中编写 switch 语句？

How do I write a switch statement in Ruby?

推荐答案

Ruby使用 case 表达式。

Ruby uses the case expression instead.

case x
when 1..5
  "It's between 1 and 5"
when 6
  "It's 6"
when "foo", "bar"
  "It's either foo or bar"
when String
  "You passed a string"
else
  "You gave me #{x} -- I have no idea what to do with that."
end

Ruby在时比较对象子句，并使用 === 运算符将对象放在 case 子句中。例如， 1..5 === x ，而不是 x === 1..5 。

Ruby compares the object in the when clause with the object in the case clause using the === operator. For example, 1..5 === x, and not x === 1..5.

如上所述，这允许使用复杂的子句。可以测试范围，类和各种各样的东西，而不仅仅是相等性。

This allows for sophisticated when clauses as seen above. Ranges, classes and all sorts of things can be tested for rather than just equality.

与 switch 语句不同其他语言，Ruby的案例没有 fall- ，因此无需在每个结束时以终止。您还可以在单​​个 when 子句中指定多个匹配项，例如 when， foo， bar 时。

Unlike switch statements in many other languages, Ruby’s case does not have fall-through, so there is no need to end each when with a break. You can also specify multiple matches in a single when clause like when "foo", "bar".

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