元组是以逗号分隔的值集合.这些用于创建临时数据结构,将相关值组合在一起.
例如,("Zara Ali","Hyderabad",10)是一个带有两个字符串的3元组值和一个int值,它具有类型(string * string * int).
元组可以是对,三元组等,具有相同或不同的类型.
此处提供了一些示例 :
// Tuple of two integers. ( 4, 5 ) // Triple of strings. ( "one", "two", "three" ) // Tuple of unknown types. ( a, b ) // Tuple that has mixed types. ( "Absolute Classes", 1, 2.0 ) // Tuple of integer expressions. ( a * 4, b + 7)
此程序具有以下功能:四个浮点值的元组并返回平均值:
let averageFour (a, b, c, d) = let sum = a + b + c + d sum / 4.0 let avg:float = averageFour (4.0, 5.1, 8.0, 12.0) printfn "Avg of four numbers: %f" avg
编译并执行程序时,它会产生以下输出 :
Avg of four numbers: 7.275000
元组的各个成员可以使用模式匹配进行评估和打印.
以下示例说明了概念 :
let display tuple1 = match tuple1 with | (a, b, c) -> printfn "Detail Info: %A %A %A" a b c display ("Zara Ali", "Hyderabad", 10 )
编译并执行程序时,它会产生以下输出 :
Detail Info: "Zara Ali" "Hyderabad" 10
F#有两个内置函数, fst 和 snd,,它们返回第一个和第二个项目在2元组中.
以下示例说明概念 :
printfn "First member: %A" (fst(23, 30)) printfn "Second member: %A" (snd(23, 30)) printfn "First member: %A" (fst("Hello", "World!")) printfn "Second member: %A" (snd("Hello", "World!")) let nameTuple = ("Zara", "Ali") printfn "First Name: %A" (fst nameTuple) printfn "Second Name: %A" (snd nameTuple)
编译并执行程序时,它会产生以下输出 :
First member: 23 Second member: 30 First member: "Hello" Second member: "World!" First Name: "Zara" Second Name: "Ali"