Enum.HasFlag(Enum) Méthode

Définition

Espace de noms:

System

Assembly:

System.Runtime.dll

Source:

Enum.cs

Détermine si un ou plusieurs champs de bits sont définis dans l'instance actuelle.

public:
 bool HasFlag(Enum ^ flag);

public bool HasFlag (Enum flag);

member this.HasFlag : Enum -> bool

Public Function HasFlag (flag As Enum) As Boolean

Paramètres

flag

Enum

Valeur d'énumération.

Retours

Boolean

true si le ou les champs de bits définis dans flag sont également définis dans l’instance actuelle ; sinon, false.

Exceptions

ArgumentException

flag est un type différent de l’instance actuelle.

Exemples

L’exemple suivant définit une DinnerItems énumération qui reflète les catégories d’articles qu’un client peut commander dans un restaurant. L’exemple teste si le client a commandé à la fois une entrée et une boisson.

using System;

[Flags] public enum DinnerItems {
   None = 0,
   Entree = 1,
   Appetizer = 2,
   Side = 4,
   Dessert = 8,
   Beverage = 16,
   BarBeverage = 32
}

public class Example
{
   public static void Main()
   {
      DinnerItems myOrder = DinnerItems.Appetizer | DinnerItems.Entree |
                            DinnerItems.Beverage | DinnerItems.Dessert;
      DinnerItems flagValue = DinnerItems.Entree | DinnerItems.Beverage;
      Console.WriteLine("{0} includes {1}: {2}",
                        myOrder, flagValue, myOrder.HasFlag(flagValue));
   }
}
// The example displays the following output:
//    Entree, Appetizer, Dessert, Beverage includes Entree, Beverage: True

open System

[<Flags>] 
type DinnerItems =
    | None = 0
    | Entree = 1
    | Appetizer = 2
    | Side = 4
    | Dessert = 8
    | Beverage = 16
    | BarBeverage = 32

let myOrder = 
    DinnerItems.Appetizer ||| DinnerItems.Entree ||| DinnerItems.Beverage ||| DinnerItems.Dessert
let flagValue = 
    DinnerItems.Entree ||| DinnerItems.Beverage
printfn $"{myOrder} includes {flagValue}: {myOrder.HasFlag flagValue}"
// The example displays the following output:
//    Entree, Appetizer, Dessert, Beverage includes Entree, Beverage: True

<Flags> Public Enum DinnerItems As Integer
   None = 0
   Entree = 1
   Appetizer = 2
   Side = 4
   Dessert = 8
   Beverage = 16 
   BarBeverage = 32
End Enum

Module Example
   Public Sub Main()
      Dim myOrder As DinnerItems = DinnerItems.Appetizer Or DinnerItems.Entree Or
                                   DinnerItems.Beverage Or DinnerItems.Dessert
      Dim flagValue As DinnerItems = DinnerItems.Entree Or DinnerItems.Beverage
      Console.WriteLine("{0} includes {1}: {2}", 
                        myOrder, flagValue, myOrder.HasFlag(flagValue))
   End Sub
End Module
' The example displays the following output:
'    Entree, Appetizer, Dessert, Beverage includes Entree, Beverage: True

Remarques

La HasFlag méthode retourne le résultat de l’expression booléenne suivante.

(thisInstance & flag) == flag

Si la valeur sous-jacente de flag est zéro, la méthode retourne true. Si ce comportement n’est pas souhaitable, vous pouvez utiliser la méthode pour tester l’égalité Equals avec zéro et appeler HasFlag uniquement si la valeur sous-jacente de est différente de flag zéro, comme l’illustre l’exemple suivant.

using System;

[Flags] public enum Pets {
   None = 0,
   Dog = 1,
   Cat = 2,
   Bird = 4,
   Rabbit = 8,
   Other = 16
}

public class Example
{
   public static void Main()
   {
      Pets[] petsInFamilies = { Pets.None, Pets.Dog | Pets.Cat, Pets.Dog };
      int familiesWithoutPets = 0;
      int familiesWithDog = 0;

      foreach (var petsInFamily in petsInFamilies)
      {
         // Count families that have no pets.
         if (petsInFamily.Equals(Pets.None))
            familiesWithoutPets++;
         // Of families with pets, count families that have a dog.
         else if (petsInFamily.HasFlag(Pets.Dog))
            familiesWithDog++;
      }
      Console.WriteLine("{0} of {1} families in the sample have no pets.",
                        familiesWithoutPets, petsInFamilies.Length);
      Console.WriteLine("{0} of {1} families in the sample have a dog.",
                        familiesWithDog, petsInFamilies.Length);
   }
}
// The example displays the following output:
//       1 of 3 families in the sample have no pets.
//       2 of 3 families in the sample have a dog.

open System

[<Flags>] 
type Pets =
    | None = 0
    | Dog = 1
    | Cat = 2
    | Bird = 4
    | Rabbit = 8
    | Other = 16

let petsInFamilies = [| Pets.None; Pets.Dog ||| Pets.Cat; Pets.Dog |]
let mutable familiesWithoutPets = 0
let mutable familiesWithDog = 0

for petsInFamily in petsInFamilies do
    // Count families that have no pets.
    if petsInFamily.Equals Pets.None then
        familiesWithoutPets <- familiesWithoutPets + 1
    // Of families with pets, count families that have a dog.
    elif petsInFamily.HasFlag Pets.Dog then
        familiesWithDog <- familiesWithDog + 1

printfn $"{familiesWithoutPets} of {petsInFamilies.Length} families in the sample have no pets."
printfn $"{familiesWithDog} of {petsInFamilies} families in the sample have a dog."
// The example displays the following output:
//       1 of 3 families in the sample have no pets.
//       2 of 3 families in the sample have a dog.

<Flags> Public Enum Pets
   None = 0
   Dog = 1
   Cat = 2
   Bird = 4
   Rabbit = 8
   Other = 16
End Enum

Module Example
   Public Sub Main()
      Dim petsInFamilies() As Pets = { Pets.None, Pets.Dog Or Pets.Cat, Pets.Dog }
      Dim familiesWithoutPets As Integer
      Dim familiesWithDog As Integer
      
      For Each petsInFamily In petsInFamilies
         ' Count the number of families that have no pets.
         If petsInFamily.Equals(Pets.None) Then
            familiesWithoutPets += 1 
        ' Of families that have pets, count the number of families with a dog.
         Else If petsInFamily.HasFlag(Pets.Dog) Then
            familiesWithDog += 1
         End If
      Next
      Console.WriteLine("{0} of {1} families in the sample have no pets.", 
                        familiesWithoutPets, petsInFamilies.Length)   
      Console.WriteLine("{0} of {1} families in the sample have a dog.", 
                        familiesWithDog, petsInFamilies.Length)   
   End Sub
End Module
' The example displays the following output:
'       1 of 3 families in the sample have no pets.
'       2 of 3 families in the sample have a dog.

La HasFlag méthode est conçue pour être utilisée avec des types d’énumération marqués avec l’attribut FlagsAttribute et peut être utilisée pour déterminer si plusieurs champs de bits sont définis. Pour les types d’énumération qui ne sont pas marqués avec l’attribut FlagsAttribute , appelez la Equals méthode ou la CompareTo méthode .

Voir aussi

• FlagsAttribute
• Equals(Object)