String.init Function (F#)

Article
02/04/2013

Creates a new string whose characters are the results of applying a specified function to each index and concatenating the resulting strings.

Namespace/Module Path: Microsoft.FSharp.Core.String

Assembly: FSharp.Core (in FSharp.Core.dll)

// Signature:
String.init : int -> (int -> string) -> string

// Usage:
String.init count initializer

Parameters

count
Type: int

The number of strings to initialize.
initializer
Type: int -> string

The function to take an index and produce a string to be concatenated with the others.

Exceptions

Exception	Condition
ArgumentException	Thrown when count is negative.

Return Value

The constructed string.

Remarks

This function is named Initialize in compiled assemblies. If you are accessing the function from a .NET language other than F#, or through reflection, use this name.

Example

The following code shows how to use String.init.

let string1 = String.init 10 (fun i -> i.ToString())
printfn "%s" string1
let string2 = String.init 26 (fun i ->
    sprintf "%c" (char (i + int 'A')))
printfn "%s" string2

Output

0123456789
ABCDEFGHIJKLMNOPQRSTUVWXYZ

Platforms

Windows 7, Windows Vista SP2, Windows XP SP3, Windows XP x64 SP2, Windows Server 2008 R2, Windows Server 2008 SP2, Windows Server 2003 SP2

Version Information

F# Runtime

Supported in: 2.0, 4.0

Silverlight

Supported in: 3

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