F#中嵌套if语句

在F＃编程中总是合法的，如果/ then或if / then / else语句，这意味着你可以在另一个if或else if语句中使用一个if或else语句。

语法

if expr then
   expr
   if expr then
      expr
   else
      expr
else
   expr

实例

let a : int32 = 100
let b : int32 = 200

(* check the boolean condition using if statement *)

if (a = 100) then
(* if condition is true then check the following *)

   if (b = 200) then
      printfn "Value of a is 100 and b is 200\n"
printfn "Exact value of a is: %d" a
printfn "Exact value of b is: %d" b

编译和执行程序时，将产生以下输出

Value of a is 100 and b is 200

Exact value of a is: 100
Exact value of b is: 200