F#中if/else语句

if / then语句后面可以有一个可选的else语句，当布尔表达式为false时执行。

语法

if expr then
   expr
else
   expr

流程图

例子

let a : int32 = 100

(* check the boolean condition using if statement *)

if (a < 20) then
   printfn "a is less than 20\n"
else
   printfn "a is not less than 20\n"
   printfn "Value of a is: %d" a

当编译和执行程序时，它会产生以下输出 -

a is not less than 20

Value of a is: 100