# if

## if .. then .. else .., ternary operator

The ternary operator if-then-else takes a Boolean as first argument, and two identically typed values as second and third arguments. The resulting syntax if c then a else b is treated as an expression.

table T = with
[| as A, as B, as C |]
[| 1,    0,    true |]
[| 2,    3,    false |]
[| 4,    5,    false |]

show table "" a1d3 with
T.A
T.B
T.C
if T.C then T.A else T.B


In many languages (C, C++, Java, C#, ..), the ternary operator is written condition ? if_true : if_false.

A multi-line syntax is also available. The else keywords are indented (relative to the first line), and the expressions are further indented (relative to the else keywords):

a = 42
x = if random.binomial(0.5) then
a + 1
else if random.binomial(0.5) then
a + 2
else
a + 3

show scalar "x" with x


For aesthetic reasons, it is recommended to align the else vertically with the first if, though that is not required.

## if .. else .., branch statement

The if statement introduces a branch block within a user-defined function.

def pure mySwap(x: number, y: number) with
a = 0
b = 0
if x > y
a = y
b = x
else if x == y
a = x
b = x
else
a = x
b = y
return (a, b)

x, y = mySwap(4, 2)

show summary "" a1b1 with x, y


It is also possible to place return statements within the branches.

def pure mySwap(x: number, y: number) with
if x > y
return (y, x)
else if x == y
return (x, x)
else
return (x, y)

x, y = mySwap(4, 2)

show summary "" a1b1 with x, y


The if statement is not allowed outside the declaration of user-defined functions.

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