Scala向下或减少for循环? [英] Scala downwards or decreasing for loop?

问题描述

在 Scala 中，您经常使用迭代器以递增顺序执行 for 循环，例如:

In Scala, you often use an iterator to do a for loop in an increasing order like:

for(i <- 1 to 10){ code }

你会怎么做，让它从 10 变成 1?我猜 10 to 1 给出了一个空迭代器(就像通常的范围数学一样)?

How would you do it so it goes from 10 to 1? I guess 10 to 1 gives an empty iterator (like usual range mathematics)?

我制作了一个 Scala 脚本，它通过在迭代器上调用 reverse 来解决它，但在我看来这并不好，下面是要走的路吗?

I made a Scala script which solves it by calling reverse on the iterator, but it's not nice in my opinion, is the following the way to go?

def nBeers(n:Int) = n match {

    case 0 => ("No more bottles of beer on the wall, no more bottles of beer." +
               "
Go to the store and buy some more, " +
               "99 bottles of beer on the wall.
")

    case _ => (n + " bottles of beer on the wall, " + n +
               " bottles of beer.
" +
               "Take one down and pass it around, " +
              (if((n-1)==0)
                   "no more"
               else
                   (n-1)) +
                   " bottles of beer on the wall.
")
}

for(b <- (0 to 99).reverse)
    println(nBeers(b))

推荐答案

scala> 10 to 1 by -1
res1: scala.collection.immutable.Range = Range(10, 9, 8, 7, 6, 5, 4, 3, 2, 1)

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