F#如何循环从-1到1或1到-1？

Question

我想要一些像j = 1 .. j = -1和i = -1 .. i = 1的东西,我知道Java/C#的做法,但不是F#.

   for j in 1 .. -1 do
    for i in -1 .. 1 do
      //all 9 combination.

请指导,谢谢.

Answer 1

当循环到一个号码,你可以使用关键字DOWNTO:

for j = 1 downto -1 do
  for i = -1 to 1 do

或者您可以在@Jaya的答案中使用for in range语法.

Answer 2

   for j in 1.. -1 .. -1 do
     for i in -1 .. 1 .. 1 do
        printf "%d , %d" i j