if. 控制結構 is used in 明確 定義
(:).if. T do. B end. if. T do. B else. B1 end. if. T do. B elseif. T1 do. elseif. T2 do. B2 end.last 句子 executed in a T block is tested for a non-zero value in its leading 原子, determining wher B block after do. or rest of 句子 is executed. An empty T block result or an omitted T block tests true. See also select. 控制結構. |
plus=: 4 : 0 Addition on 非負整數s
if. y. do. >: x. plus <: y. else. x. end.
)
plus"0/~ i.5
0 1 2 3 4
1 2 3 4 5
2 3 4 5 6
3 4 5 6 7
4 5 6 7 8
sel=: 1 : 'x. # ['
q排序=: 3 : 0
if. 1 >: #y. do. y.
else.
(q排序y.<sel e),(y.=sel e),q排序y.>sel e=.y.{~?#y.
end.
)
q排序15 2 9 10 4 0 13 13 18 7
0 2 4 7 9 10 13 13 15 18
test=: 3 : 0
if. 0<y. do. 'positive'
elseif. 0>y. do. 'negative'
elseif. do. 'zero'
end.
)
test&.> 5 _2.71828 0
+--------+--------+----+
|positive|negative|zero|
+--------+--------+----+
test&.> '' ; 0 1 _2 ; _3 9
+--------+----+--------+
|positive|zero|negative|
+--------+----+--------+