String.exists Function (F#)

Tests if any character of the string satisfies the given predicate.

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

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

// Signature:
String.exists : (char -> bool) -> string -> bool

// Usage:
String.exists predicate str

Parameters

• predicate
  Type: char -> bool

  The function to test each character of the string.

• str
  Type: string

  The input string.

Exceptions

Exception	Condition
ArgumentNullException	Thrown when the input string is null.

Return Value

Returns true if any character returns true for the predicate and false otherwise.

Remarks

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

Example

The following code shows how to use String.exists.

let containsUppercase string1 =
    if (String.exists (fun c -> System.Char.IsUpper(c)) string1) then
        printfn "The string \"%s\" contains uppercase characters." string1
    else
        printfn "The string \"%s\" does not contain uppercase characters." string1
containsUppercase "Hello World!"
containsUppercase "no"

Output

The string "Hello World!" contains uppercase characters.
The string "no" does not contain uppercase characters.

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

See Also

Reference

Core.String Module (F#)

Microsoft.FSharp.Core Namespace (F#)