String.init Function (F#)

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

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 8, Windows 7, Windows Server 2012, Windows Server 2008 R2

Version Information

F# Core Library Versions

Supported in: 2.0, 4.0, Portable

See Also

Reference

Core.String Module (F#)

Microsoft.FSharp.Core Namespace (F#)