在Scala中将for循环递增2

Question

如何将循环增加2，相当于Java中的循环：

for (int i = 0; i < max; i+=2)

现在在Scala中，我有：

for (a <- 0 to max)

实际上， max永远是偶数。 我不知道如何在每个循环中将计数器增加到2。

Answer 1

尝试for (a <- 0 until max by 2)

Answer 2

注意to和until之间的区别。 严格的i < max你会想要直到。

val max = 10

scala> for(i <- 0 until max by 2)
     | println(i)
0
2
4
6
8

scala> for(i <- 0 to max by 2)
     | println(i)
0
2
4
6
8
10

Answer 3

这样，您可以将scala用于像java one这样的循环。

object Example extends App {
    for(i <-0 to 20 by 2) {
        println("Value of i = "+ i)
    }
}

输出量

Value of i = 0
Value of i = 2
Value of i = 4
Value of i = 6
Value of i = 8
Value of i = 10
Value of i = 12
Value of i = 14
Value of i = 16
Value of i = 18
Value of i = 20

Answer 4

毫不奇怪的是：

scala> for (a <- 0 until 10 by 2) yield a
// Vector(0, 2, 4, 6, 8, 10)

Answer 5

for (a <- 0 to max by 2) yield a

Answer 6

一定

(0 until max by 2)  foreach {...}

就足够了。