Char Struct

Definizione

public value class char : IComparable, IComparable<char>, IConvertible, IEquatable<char>

public value class char : IComparable<char>, IConvertible, IEquatable<char>, IParsable<char>, ISpanParsable<char>, IUtf8SpanParsable<char>, System::Numerics::IAdditionOperators<char, char, char>, System::Numerics::IAdditiveIdentity<char, char>, System::Numerics::IBinaryInteger<char>, System::Numerics::IBinaryNumber<char>, System::Numerics::IBitwiseOperators<char, char, char>, System::Numerics::IComparisonOperators<char, char, bool>, System::Numerics::IDecrementOperators<char>, System::Numerics::IDivisionOperators<char, char, char>, System::Numerics::IEqualityOperators<char, char, bool>, System::Numerics::IIncrementOperators<char>, System::Numerics::IMinMaxValue<char>, System::Numerics::IModulusOperators<char, char, char>, System::Numerics::IMultiplicativeIdentity<char, char>, System::Numerics::IMultiplyOperators<char, char, char>, System::Numerics::INumber<char>, System::Numerics::INumberBase<char>, System::Numerics::IShiftOperators<char, int, char>, System::Numerics::ISubtractionOperators<char, char, char>, System::Numerics::IUnaryNegationOperators<char, char>, System::Numerics::IUnaryPlusOperators<char, char>, System::Numerics::IUnsignedNumber<char>

public value class char : IComparable, IComparable<char>, IConvertible, IEquatable<char>, ISpanFormattable

public value class char : IComparable<char>, IConvertible, IEquatable<char>, IParsable<char>, ISpanParsable<char>, System::Numerics::IAdditionOperators<char, char, char>, System::Numerics::IAdditiveIdentity<char, char>, System::Numerics::IBinaryInteger<char>, System::Numerics::IBinaryNumber<char>, System::Numerics::IBitwiseOperators<char, char, char>, System::Numerics::IComparisonOperators<char, char, bool>, System::Numerics::IDecrementOperators<char>, System::Numerics::IDivisionOperators<char, char, char>, System::Numerics::IEqualityOperators<char, char, bool>, System::Numerics::IIncrementOperators<char>, System::Numerics::IMinMaxValue<char>, System::Numerics::IModulusOperators<char, char, char>, System::Numerics::IMultiplicativeIdentity<char, char>, System::Numerics::IMultiplyOperators<char, char, char>, System::Numerics::INumber<char>, System::Numerics::INumberBase<char>, System::Numerics::IShiftOperators<char, int, char>, System::Numerics::ISubtractionOperators<char, char, char>, System::Numerics::IUnaryNegationOperators<char, char>, System::Numerics::IUnaryPlusOperators<char, char>, System::Numerics::IUnsignedNumber<char>

public value class char : IComparable, IConvertible

public value class char : IComparable, IComparable<char>, IEquatable<char>

public struct Char : IComparable, IComparable<char>, IConvertible, IEquatable<char>

public readonly struct Char : IComparable<char>, IConvertible, IEquatable<char>, IParsable<char>, ISpanParsable<char>, IUtf8SpanParsable<char>, System.Numerics.IAdditionOperators<char,char,char>, System.Numerics.IAdditiveIdentity<char,char>, System.Numerics.IBinaryInteger<char>, System.Numerics.IBinaryNumber<char>, System.Numerics.IBitwiseOperators<char,char,char>, System.Numerics.IComparisonOperators<char,char,bool>, System.Numerics.IDecrementOperators<char>, System.Numerics.IDivisionOperators<char,char,char>, System.Numerics.IEqualityOperators<char,char,bool>, System.Numerics.IIncrementOperators<char>, System.Numerics.IMinMaxValue<char>, System.Numerics.IModulusOperators<char,char,char>, System.Numerics.IMultiplicativeIdentity<char,char>, System.Numerics.IMultiplyOperators<char,char,char>, System.Numerics.INumber<char>, System.Numerics.INumberBase<char>, System.Numerics.IShiftOperators<char,int,char>, System.Numerics.ISubtractionOperators<char,char,char>, System.Numerics.IUnaryNegationOperators<char,char>, System.Numerics.IUnaryPlusOperators<char,char>, System.Numerics.IUnsignedNumber<char>

public readonly struct Char : IComparable, IComparable<char>, IConvertible, IEquatable<char>

public readonly struct Char : IComparable, IComparable<char>, IConvertible, IEquatable<char>, ISpanFormattable

public readonly struct Char : IComparable<char>, IConvertible, IEquatable<char>, IParsable<char>, ISpanParsable<char>, System.Numerics.IAdditionOperators<char,char,char>, System.Numerics.IAdditiveIdentity<char,char>, System.Numerics.IBinaryInteger<char>, System.Numerics.IBinaryNumber<char>, System.Numerics.IBitwiseOperators<char,char,char>, System.Numerics.IComparisonOperators<char,char,bool>, System.Numerics.IDecrementOperators<char>, System.Numerics.IDivisionOperators<char,char,char>, System.Numerics.IEqualityOperators<char,char,bool>, System.Numerics.IIncrementOperators<char>, System.Numerics.IMinMaxValue<char>, System.Numerics.IModulusOperators<char,char,char>, System.Numerics.IMultiplicativeIdentity<char,char>, System.Numerics.IMultiplyOperators<char,char,char>, System.Numerics.INumber<char>, System.Numerics.INumberBase<char>, System.Numerics.IShiftOperators<char,int,char>, System.Numerics.ISubtractionOperators<char,char,char>, System.Numerics.IUnaryNegationOperators<char,char>, System.Numerics.IUnaryPlusOperators<char,char>, System.Numerics.IUnsignedNumber<char>

[System.Serializable]
public struct Char : IComparable, IConvertible

[System.Serializable]
[System.Runtime.InteropServices.ComVisible(true)]
public struct Char : IComparable, IComparable<char>, IConvertible, IEquatable<char>

public struct Char : IComparable, IComparable<char>, IEquatable<char>

type char = struct
    interface IConvertible

type char = struct
    interface IConvertible
    interface IFormattable
    interface IParsable<char>
    interface ISpanFormattable
    interface ISpanParsable<char>
    interface IUtf8SpanFormattable
    interface IUtf8SpanParsable<char>
    interface IAdditionOperators<char, char, char>
    interface IAdditiveIdentity<char, char>
    interface IBinaryInteger<char>
    interface IBinaryNumber<char>
    interface IBitwiseOperators<char, char, char>
    interface IComparisonOperators<char, char, bool>
    interface IEqualityOperators<char, char, bool>
    interface IDecrementOperators<char>
    interface IDivisionOperators<char, char, char>
    interface IIncrementOperators<char>
    interface IModulusOperators<char, char, char>
    interface IMultiplicativeIdentity<char, char>
    interface IMultiplyOperators<char, char, char>
    interface INumber<char>
    interface INumberBase<char>
    interface ISubtractionOperators<char, char, char>
    interface IUnaryNegationOperators<char, char>
    interface IUnaryPlusOperators<char, char>
    interface IShiftOperators<char, int, char>
    interface IMinMaxValue<char>
    interface IUnsignedNumber<char>

type char = struct
    interface IConvertible
    interface ISpanFormattable
    interface IFormattable

type char = struct
    interface IConvertible
    interface IFormattable
    interface IParsable<char>
    interface ISpanFormattable
    interface ISpanParsable<char>
    interface IAdditionOperators<char, char, char>
    interface IAdditiveIdentity<char, char>
    interface IBinaryInteger<char>
    interface IBinaryNumber<char>
    interface IBitwiseOperators<char, char, char>
    interface IComparisonOperators<char, char, bool>
    interface IEqualityOperators<char, char, bool>
    interface IDecrementOperators<char>
    interface IDivisionOperators<char, char, char>
    interface IIncrementOperators<char>
    interface IModulusOperators<char, char, char>
    interface IMultiplicativeIdentity<char, char>
    interface IMultiplyOperators<char, char, char>
    interface INumber<char>
    interface INumberBase<char>
    interface ISubtractionOperators<char, char, char>
    interface IUnaryNegationOperators<char, char>
    interface IUnaryPlusOperators<char, char>
    interface IShiftOperators<char, int, char>
    interface IMinMaxValue<char>
    interface IUnsignedNumber<char>

type char = struct
    interface IConvertible
    interface IFormattable
    interface IParsable<char>
    interface ISpanFormattable
    interface ISpanParsable<char>
    interface IAdditionOperators<char, char, char>
    interface IAdditiveIdentity<char, char>
    interface IBinaryInteger<char>
    interface IBinaryNumber<char>
    interface IBitwiseOperators<char, char, char>
    interface IComparisonOperators<char, char, bool>
    interface IEqualityOperators<char, char, bool>
    interface IDecrementOperators<char>
    interface IDivisionOperators<char, char, char>
    interface IIncrementOperators<char>
    interface IModulusOperators<char, char, char>
    interface IMultiplicativeIdentity<char, char>
    interface IMultiplyOperators<char, char, char>
    interface INumber<char>
    interface INumberBase<char>
    interface ISubtractionOperators<char, char, char>
    interface IUnaryNegationOperators<char, char>
    interface IUnaryPlusOperators<char, char>
    interface IUtf8SpanFormattable
    interface IUtf8SpanParsable<char>
    interface IShiftOperators<char, int, char>
    interface IMinMaxValue<char>
    interface IUnsignedNumber<char>

[<System.Serializable>]
type char = struct
    interface IConvertible

[<System.Serializable>]
[<System.Runtime.InteropServices.ComVisible(true)>]
type char = struct
    interface IConvertible

type char = struct

Public Structure Char
Implements IComparable, IComparable(Of Char), IConvertible, IEquatable(Of Char)

Public Structure Char
Implements IAdditionOperators(Of Char, Char, Char), IAdditiveIdentity(Of Char, Char), IBinaryInteger(Of Char), IBinaryNumber(Of Char), IBitwiseOperators(Of Char, Char, Char), IComparable(Of Char), IComparisonOperators(Of Char, Char, Boolean), IConvertible, IDecrementOperators(Of Char), IDivisionOperators(Of Char, Char, Char), IEqualityOperators(Of Char, Char, Boolean), IEquatable(Of Char), IIncrementOperators(Of Char), IMinMaxValue(Of Char), IModulusOperators(Of Char, Char, Char), IMultiplicativeIdentity(Of Char, Char), IMultiplyOperators(Of Char, Char, Char), INumber(Of Char), INumberBase(Of Char), IParsable(Of Char), IShiftOperators(Of Char, Integer, Char), ISpanParsable(Of Char), ISubtractionOperators(Of Char, Char, Char), IUnaryNegationOperators(Of Char, Char), IUnaryPlusOperators(Of Char, Char), IUnsignedNumber(Of Char), IUtf8SpanParsable(Of Char)

Public Structure Char
Implements IComparable, IComparable(Of Char), IConvertible, IEquatable(Of Char), ISpanFormattable

Public Structure Char
Implements IAdditionOperators(Of Char, Char, Char), IAdditiveIdentity(Of Char, Char), IBinaryInteger(Of Char), IBinaryNumber(Of Char), IBitwiseOperators(Of Char, Char, Char), IComparable(Of Char), IComparisonOperators(Of Char, Char, Boolean), IConvertible, IDecrementOperators(Of Char), IDivisionOperators(Of Char, Char, Char), IEqualityOperators(Of Char, Char, Boolean), IEquatable(Of Char), IIncrementOperators(Of Char), IMinMaxValue(Of Char), IModulusOperators(Of Char, Char, Char), IMultiplicativeIdentity(Of Char, Char), IMultiplyOperators(Of Char, Char, Char), INumber(Of Char), INumberBase(Of Char), IParsable(Of Char), IShiftOperators(Of Char, Integer, Char), ISpanParsable(Of Char), ISubtractionOperators(Of Char, Char, Char), IUnaryNegationOperators(Of Char, Char), IUnaryPlusOperators(Of Char, Char), IUnsignedNumber(Of Char)

Public Structure Char
Implements IComparable, IConvertible

Public Structure Char
Implements IComparable, IComparable(Of Char), IEquatable(Of Char)

Ereditarietà

Object

ValueType

Char

Attributi

SerializableAttribute ComVisibleAttribute

Implementazioni

IComparable IComparable<Char> IConvertible IEquatable<Char> IComparable<TSelf> IEquatable<TSelf> IFormattable IParsable<Char> IParsable<TSelf> ISpanFormattable ISpanParsable<Char> ISpanParsable<TSelf> IUtf8SpanFormattable IUtf8SpanParsable<Char> IUtf8SpanParsable<TSelf> IAdditionOperators<Char,Char,Char> IAdditionOperators<TSelf,TSelf,TSelf> IAdditiveIdentity<Char,Char> IAdditiveIdentity<TSelf,TSelf> IBinaryInteger<Char> IBinaryNumber<Char> IBinaryNumber<TSelf> IBitwiseOperators<Char,Char,Char> IBitwiseOperators<TSelf,TSelf,TSelf> IComparisonOperators<Char,Char,Boolean> IComparisonOperators<TSelf,TSelf,Boolean> IDecrementOperators<Char> IDecrementOperators<TSelf> IDivisionOperators<Char,Char,Char> IDivisionOperators<TSelf,TSelf,TSelf> IEqualityOperators<Char,Char,Boolean> IEqualityOperators<TSelf,TOther,TResult> IEqualityOperators<TSelf,TSelf,Boolean> IIncrementOperators<Char> IIncrementOperators<TSelf> IMinMaxValue<Char> IModulusOperators<Char,Char,Char> IModulusOperators<TSelf,TSelf,TSelf> IMultiplicativeIdentity<Char,Char> IMultiplicativeIdentity<TSelf,TSelf> IMultiplyOperators<Char,Char,Char> IMultiplyOperators<TSelf,TSelf,TSelf> INumber<Char> INumber<TSelf> INumberBase<Char> INumberBase<TSelf> IShiftOperators<Char,Int32,Char> IShiftOperators<TSelf,Int32,TSelf> ISubtractionOperators<Char,Char,Char> ISubtractionOperators<TSelf,TSelf,TSelf> IUnaryNegationOperators<Char,Char> IUnaryNegationOperators<TSelf,TSelf> IUnaryPlusOperators<Char,Char> IUnaryPlusOperators<TSelf,TSelf> IUnsignedNumber<Char>

Esempio

Nell'esempio di codice seguente vengono illustrati alcuni dei metodi in Char.

using System;

public class CharStructureSample
{
    public static void Main()
    {
        char chA = 'A';
        char ch1 = '1';
        string str = "test string";

        Console.WriteLine(chA.CompareTo('B'));          //-----------  Output: "-1" (meaning 'A' is 1 less than 'B')
        Console.WriteLine(chA.Equals('A'));             //-----------  Output: "True"
        Console.WriteLine(Char.GetNumericValue(ch1));   //-----------  Output: "1"
        Console.WriteLine(Char.IsControl('\t'));        //-----------  Output: "True"
        Console.WriteLine(Char.IsDigit(ch1));           //-----------  Output: "True"
        Console.WriteLine(Char.IsLetter(','));          //-----------  Output: "False"
        Console.WriteLine(Char.IsLower('u'));           //-----------  Output: "True"
        Console.WriteLine(Char.IsNumber(ch1));          //-----------  Output: "True"
        Console.WriteLine(Char.IsPunctuation('.'));     //-----------  Output: "True"
        Console.WriteLine(Char.IsSeparator(str, 4));    //-----------  Output: "True"
        Console.WriteLine(Char.IsSymbol('+'));          //-----------  Output: "True"
        Console.WriteLine(Char.IsWhiteSpace(str, 4));   //-----------  Output: "True"
        Console.WriteLine(Char.Parse("S"));             //-----------  Output: "S"
        Console.WriteLine(Char.ToLower('M'));           //-----------  Output: "m"
        Console.WriteLine('x'.ToString());              //-----------  Output: "x"
    }
}

open System

let chA = 'A'
let ch1 = '1'
let str = "test string"

printfn $"{chA.CompareTo 'B'}"          //-----------  Output: "-1" (meaning 'A' is 1 less than 'B')
printfn $"{chA.Equals 'A'}"             //-----------  Output: "True"
printfn $"{Char.GetNumericValue ch1}"   //-----------  Output: "1"
printfn $"{Char.IsControl '\t'}"        //-----------  Output: "True"
printfn $"{Char.IsDigit ch1}"           //-----------  Output: "True"
printfn $"{Char.IsLetter ','}"          //-----------  Output: "False"
printfn $"{Char.IsLower 'u'}"           //-----------  Output: "True"
printfn $"{Char.IsNumber ch1}"          //-----------  Output: "True"
printfn $"{Char.IsPunctuation '.'}"     //-----------  Output: "True"
printfn $"{Char.IsSeparator(str, 4)}"   //-----------  Output: "True"
printfn $"{Char.IsSymbol '+'}"          //-----------  Output: "True"
printfn $"{Char.IsWhiteSpace(str, 4)}"  //-----------  Output: "True"
printfn $"""{Char.Parse "S"}"""         //-----------  Output: "S"
printfn $"{Char.ToLower 'M'}"           //-----------  Output: "m"
printfn $"{'x'}"                        //-----------  Output: "x"

Module CharStructure

    Public Sub Main()

        Dim chA As Char
        chA = "A"c
        Dim ch1 As Char
        ch1 = "1"c
        Dim str As String
        str = "test string"

        Console.WriteLine(chA.CompareTo("B"c))          ' Output: "-1" (meaning 'A' is 1 less than 'B')
        Console.WriteLine(chA.Equals("A"c))             ' Output: "True"
        Console.WriteLine(Char.GetNumericValue(ch1))    ' Output: "1"
        Console.WriteLine(Char.IsControl(Chr(9)))       ' Output: "True"
        Console.WriteLine(Char.IsDigit(ch1))            ' Output: "True"
        Console.WriteLine(Char.IsLetter(","c))          ' Output: "False"
        Console.WriteLine(Char.IsLower("u"c))           ' Output: "True"
        Console.WriteLine(Char.IsNumber(ch1))           ' Output: "True"
        Console.WriteLine(Char.IsPunctuation("."c))     ' Output: "True"
        Console.WriteLine(Char.IsSeparator(str, 4))     ' Output: "True"
        Console.WriteLine(Char.IsSymbol("+"c))          ' Output: "True"
        Console.WriteLine(Char.IsWhiteSpace(str, 4))    ' Output: "True"
        Console.WriteLine(Char.Parse("S"))              ' Output: "S"
        Console.WriteLine(Char.ToLower("M"c))           ' Output: "m"
        Console.WriteLine("x"c.ToString())              ' Output: "x"

    End Sub

End Module

Commenti

La struttura Char rappresenta i punti di codice Unicode usando la codifica UTF-16. Il valore di un oggetto Char è il valore numerico a 16 bit (ordinale).

Se non si ha familiarità con Unicode, valori scalari, punti codice, coppie di surrogati, UTF-16 e tipo Rune, vedere Introduzione alla codifica dei caratteri in .NET.

Questo articolo esamina la relazione tra un oggetto Char e un carattere e illustra alcune attività comuni eseguite con Char istanze. È consigliabile considerare il tipo di Rune, introdotto in .NET Core 3.0, come alternativa a Char per eseguire alcune di queste attività.

Oggetti Char, caratteri Unicode e stringhe

Un oggetto String è una raccolta sequenziale di strutture Char che rappresenta una stringa di testo. La maggior parte dei caratteri Unicode può essere rappresentata da un singolo oggetto Char, ma un carattere codificato come carattere di base, coppia di surrogati e/o sequenza di caratteri combinati è rappresentato da più oggetti Char. Per questo motivo, una struttura Char in un oggetto String non è necessariamente equivalente a un singolo carattere Unicode.

Più unità di codice a 16 bit vengono usate per rappresentare singoli caratteri Unicode nei casi seguenti:

• Glifi, che possono essere costituiti da un singolo carattere o da un carattere di base seguito da uno o più caratteri combinati. Ad esempio, il carattere ä è rappresentato da un oggetto Char la cui unità di codice è U+0061 seguita da un oggetto Char la cui unità di codice è U+0308. Il carattere ä può essere definito anche da un singolo oggetto Char con un'unità di codice U+00E4. Nell'esempio seguente viene illustrato che il carattere ä è costituito da due oggetti Char.

  using System;
  using System.IO;
  
  public class Example1
  {
      public static void Main()
      {
          StreamWriter sw = new StreamWriter("chars1.txt");
          char[] chars = [ '\u0061', '\u0308' ];
          string strng = new String(chars);
          sw.WriteLine(strng);
          sw.Close();
      }
  }
  // The example produces the following output:
  //       ä
  

  open System
  open System.IO
  
  let sw = new StreamWriter("chars1.txt")
  let chars = [| '\u0061'; '\u0308' |]
  let string = String chars
  sw.WriteLine string
  sw.Close()
  
  // The example produces the following output:
  //       ä
  

  Imports System.IO
  
  Module Example2
      Public Sub Main()
          Dim sw As New StreamWriter("chars1.txt")
          Dim chars() As Char = {ChrW(&H61), ChrW(&H308)}
          Dim strng As New String(chars)
          sw.WriteLine(strng)
          sw.Close()
      End Sub
  End Module
  ' The example produces the following output:
  '       ä
  

• Caratteri esterni al Piano Multilingue di Base Unicode (BMP). Unicode supporta sedici piani oltre al BMP, che rappresenta il piano 0. Un punto di codice Unicode è rappresentato in UTF-32 da un valore a 21 bit che include il piano. Ad esempio, U+1D160 rappresenta il carattere MUSICAL SYMBOL OTTAVO NOTA. Poiché la codifica UTF-16 ha solo 16 bit, i caratteri esterni al BMP sono rappresentati da coppie di surrogati in UTF-16. L'esempio seguente illustra che l'equivalente UTF-32 di U+1D160, il carattere MUSICAL SYMBOL EIGHTH NOTE, è U+D834 U+DD60. U+D834 è il surrogato alto; i surrogati alti vanno da U+D800 a U+DBFF. U+DD60 è il surrogato basso; i surrogati bassi vanno da U+DC00 a U+DFFF.

  using System;
  using System.IO;
  
  public class Example3
  {
      public static void Main()
      {
          StreamWriter sw = new StreamWriter(@".\chars2.txt");
          int utf32 = 0x1D160;
          string surrogate = Char.ConvertFromUtf32(utf32);
          sw.WriteLine($"U+{utf32:X6} UTF-32 = {surrogate} ({ShowCodePoints(surrogate)}) UTF-16");
          sw.Close();
      }
  
      private static string ShowCodePoints(string value)
      {
          string retval = null;
          foreach (var ch in value)
              retval += $"U+{Convert.ToUInt16(ch):X4} ";
  
          return retval.Trim();
      }
  }
  // The example produces the following output:
  //       U+01D160 UTF-32 = ð (U+D834 U+DD60) UTF-16
  

  open System
  open System.IO
  
  let showCodePoints (value: char seq) =
      let str =
          value
          |> Seq.map (fun ch -> $"U+{Convert.ToUInt16 ch:X4}")
          |> String.concat ""
      str.Trim()
  
  let sw = new StreamWriter(@".\chars2.txt")
  let utf32 = 0x1D160
  let surrogate = Char.ConvertFromUtf32 utf32
  sw.WriteLine $"U+{utf32:X6} UTF-32 = {surrogate} ({showCodePoints surrogate}) UTF-16"
  sw.Close()
  
  // The example produces the following output:
  //       U+01D160 UTF-32 = ð (U+D834 U+DD60) UTF-16
  

  Imports System.IO
  
  Module Example4
      Public Sub Main()
          Dim sw As New StreamWriter(".\chars2.txt")
          Dim utf32 As Integer = &H1D160
          Dim surrogate As String = Char.ConvertFromUtf32(utf32)
          sw.WriteLine("U+{0:X6} UTF-32 = {1} ({2}) UTF-16",
                     utf32, surrogate, ShowCodePoints(surrogate))
          sw.Close()
      End Sub
  
      Private Function ShowCodePoints(value As String) As String
          Dim retval As String = Nothing
          For Each ch In value
              retval += String.Format("U+{0:X4} ", Convert.ToUInt16(ch))
          Next
          Return retval.Trim()
      End Function
  End Module
  ' The example produces the following output:
  '       U+01D160 UTF-32 = ð (U+D834 U+DD60) UTF-16
  

Caratteri e categorie di caratteri

Ogni carattere Unicode o coppia di surrogati valida appartiene a una categoria Unicode. In .NET le categorie Unicode sono rappresentate dai membri dell'enumerazione UnicodeCategory e includono valori come UnicodeCategory.CurrencySymbol, UnicodeCategory.LowercaseLettere UnicodeCategory.SpaceSeparator, ad esempio.

Per determinare la categoria Unicode di un carattere, chiamare il metodo GetUnicodeCategory. Nell'esempio seguente, ad esempio, viene chiamato il GetUnicodeCategory per visualizzare la categoria Unicode di ogni carattere in una stringa. L'esempio funziona correttamente solo se nell'istanza di String non sono presenti coppie di surrogati.

using System;
using System.Globalization;

class Example
{
   public static void Main()
   {
      // Define a string with a variety of character categories.
      String s = "The red car drove down the long, narrow, secluded road.";
      // Determine the category of each character.
      foreach (var ch in s)
         Console.WriteLine($"'{ch}': {Char.GetUnicodeCategory(ch)}");
   }
}
// The example displays the following output:
//      'T': UppercaseLetter
//      'h': LowercaseLetter
//      'e': LowercaseLetter
//      ' ': SpaceSeparator
//      'r': LowercaseLetter
//      'e': LowercaseLetter
//      'd': LowercaseLetter
//      ' ': SpaceSeparator
//      'c': LowercaseLetter
//      'a': LowercaseLetter
//      'r': LowercaseLetter
//      ' ': SpaceSeparator
//      'd': LowercaseLetter
//      'r': LowercaseLetter
//      'o': LowercaseLetter
//      'v': LowercaseLetter
//      'e': LowercaseLetter
//      ' ': SpaceSeparator
//      'd': LowercaseLetter
//      'o': LowercaseLetter
//      'w': LowercaseLetter
//      'n': LowercaseLetter
//      ' ': SpaceSeparator
//      't': LowercaseLetter
//      'h': LowercaseLetter
//      'e': LowercaseLetter
//      ' ': SpaceSeparator
//      'l': LowercaseLetter
//      'o': LowercaseLetter
//      'n': LowercaseLetter
//      'g': LowercaseLetter
//      ',': OtherPunctuation
//      ' ': SpaceSeparator
//      'n': LowercaseLetter
//      'a': LowercaseLetter
//      'r': LowercaseLetter
//      'r': LowercaseLetter
//      'o': LowercaseLetter
//      'w': LowercaseLetter
//      ',': OtherPunctuation
//      ' ': SpaceSeparator
//      's': LowercaseLetter
//      'e': LowercaseLetter
//      'c': LowercaseLetter
//      'l': LowercaseLetter
//      'u': LowercaseLetter
//      'd': LowercaseLetter
//      'e': LowercaseLetter
//      'd': LowercaseLetter
//      ' ': SpaceSeparator
//      'r': LowercaseLetter
//      'o': LowercaseLetter
//      'a': LowercaseLetter
//      'd': LowercaseLetter
//      '.': OtherPunctuation

open System

// Define a string with a variety of character categories.
let s = "The red car drove down the long, narrow, secluded road."
// Determine the category of each character.
for ch in s do
    printfn $"'{ch}': {Char.GetUnicodeCategory ch}"

// The example displays the following output:
//      'T': UppercaseLetter
//      'h': LowercaseLetter
//      'e': LowercaseLetter
//      ' ': SpaceSeparator
//      'r': LowercaseLetter
//      'e': LowercaseLetter
//      'd': LowercaseLetter
//      ' ': SpaceSeparator
//      'c': LowercaseLetter
//      'a': LowercaseLetter
//      'r': LowercaseLetter
//      ' ': SpaceSeparator
//      'd': LowercaseLetter
//      'r': LowercaseLetter
//      'o': LowercaseLetter
//      'v': LowercaseLetter
//      'e': LowercaseLetter
//      ' ': SpaceSeparator
//      'd': LowercaseLetter
//      'o': LowercaseLetter
//      'w': LowercaseLetter
//      'n': LowercaseLetter
//      ' ': SpaceSeparator
//      't': LowercaseLetter
//      'h': LowercaseLetter
//      'e': LowercaseLetter
//      ' ': SpaceSeparator
//      'l': LowercaseLetter
//      'o': LowercaseLetter
//      'n': LowercaseLetter
//      'g': LowercaseLetter
//      ',': OtherPunctuation
//      ' ': SpaceSeparator
//      'n': LowercaseLetter
//      'a': LowercaseLetter
//      'r': LowercaseLetter
//      'r': LowercaseLetter
//      'o': LowercaseLetter
//      'w': LowercaseLetter
//      ',': OtherPunctuation
//      ' ': SpaceSeparator
//      's': LowercaseLetter
//      'e': LowercaseLetter
//      'c': LowercaseLetter
//      'l': LowercaseLetter
//      'u': LowercaseLetter
//      'd': LowercaseLetter
//      'e': LowercaseLetter
//      'd': LowercaseLetter
//      ' ': SpaceSeparator
//      'r': LowercaseLetter
//      'o': LowercaseLetter
//      'a': LowercaseLetter
//      'd': LowercaseLetter
//      '.': OtherPunctuation

Imports System.Globalization

Module Example1
    Public Sub Main()
        ' Define a string with a variety of character categories.
        Dim s As String = "The car drove down the narrow, secluded road."
        ' Determine the category of each character.
        For Each ch In s
            Console.WriteLine("'{0}': {1}", ch, Char.GetUnicodeCategory(ch))
        Next
    End Sub
End Module
' The example displays the following output:
'       'T': UppercaseLetter
'       'h': LowercaseLetter
'       'e': LowercaseLetter
'       ' ': SpaceSeparator
'       'r': LowercaseLetter
'       'e': LowercaseLetter
'       'd': LowercaseLetter
'       ' ': SpaceSeparator
'       'c': LowercaseLetter
'       'a': LowercaseLetter
'       'r': LowercaseLetter
'       ' ': SpaceSeparator
'       'd': LowercaseLetter
'       'r': LowercaseLetter
'       'o': LowercaseLetter
'       'v': LowercaseLetter
'       'e': LowercaseLetter
'       ' ': SpaceSeparator
'       'd': LowercaseLetter
'       'o': LowercaseLetter
'       'w': LowercaseLetter
'       'n': LowercaseLetter
'       ' ': SpaceSeparator
'       't': LowercaseLetter
'       'h': LowercaseLetter
'       'e': LowercaseLetter
'       ' ': SpaceSeparator
'       'l': LowercaseLetter
'       'o': LowercaseLetter
'       'n': LowercaseLetter
'       'g': LowercaseLetter
'       ',': OtherPunctuation
'       ' ': SpaceSeparator
'       'n': LowercaseLetter
'       'a': LowercaseLetter
'       'r': LowercaseLetter
'       'r': LowercaseLetter
'       'o': LowercaseLetter
'       'w': LowercaseLetter
'       ',': OtherPunctuation
'       ' ': SpaceSeparator
'       's': LowercaseLetter
'       'e': LowercaseLetter
'       'c': LowercaseLetter
'       'l': LowercaseLetter
'       'u': LowercaseLetter
'       'd': LowercaseLetter
'       'e': LowercaseLetter
'       'd': LowercaseLetter
'       ' ': SpaceSeparator
'       'r': LowercaseLetter
'       'o': LowercaseLetter
'       'a': LowercaseLetter
'       'd': LowercaseLetter
'       '.': OtherPunctuation

Internamente, per i caratteri esterni all'intervallo ASCII (da U+0000 a U+00FF), il metodo GetUnicodeCategory dipende dalle categorie Unicode segnalate dalla classe CharUnicodeInfo. I caratteri Unicode vengono classificati in base allo standard Unicode versione 8.0.0.

Caratteri ed elementi di testo

Poiché un singolo carattere può essere rappresentato da più oggetti Char, non è sempre significativo lavorare con singoli oggetti Char. L'esempio seguente, ad esempio, converte i punti di codice Unicode che rappresentano i numeri dell'Egeo da zero a 9 in unità di codice con codifica UTF-16. Poiché equipara erroneamente gli oggetti Char ai caratteri, riporta inaccuratamente che la stringa risultante ha 20 caratteri.

using System;

public class Example5
{
    public static void Main()
    {
        string result = String.Empty;
        for (int ctr = 0x10107; ctr <= 0x10110; ctr++)  // Range of Aegean numbers.
            result += Char.ConvertFromUtf32(ctr);

        Console.WriteLine($"The string contains {result.Length} characters.");
    }
}
// The example displays the following output:
//     The string contains 20 characters.

open System

let result =
    [ for i in 0x10107..0x10110 do  // Range of Aegean numbers.
        Char.ConvertFromUtf32 i ]
    |> String.concat ""

printfn $"The string contains {result.Length} characters."


// The example displays the following output:
//     The string contains 20 characters.

Module Example5
    Public Sub Main()
        Dim result As String = String.Empty
        For ctr As Integer = &H10107 To &H10110     ' Range of Aegean numbers.
            result += Char.ConvertFromUtf32(ctr)
        Next
        Console.WriteLine("The string contains {0} characters.", result.Length)
    End Sub
End Module
' The example displays the following output:
'     The string contains 20 characters.

È possibile eseguire le operazioni seguenti per evitare il presupposto che un oggetto Char rappresenti un singolo carattere:

• È possibile usare un oggetto String nella sua interezza invece di lavorare con i singoli caratteri per rappresentare e analizzare il contenuto linguistico.

• È possibile usare String.EnumerateRunes come illustrato nell'esempio seguente:

  int CountLetters(string s)
  {
      int letterCount = 0;
  
      foreach (Rune rune in s.EnumerateRunes())
      {
          if (Rune.IsLetter(rune))
          { letterCount++; }
      }
  
      return letterCount;
  }
  

  let countLetters (s: string) =
      let mutable letterCount = 0
  
      for rune in s.EnumerateRunes() do
          if Rune.IsLetter rune then
              letterCount <- letterCount + 1
  
      letterCount
  

• È possibile usare la classe StringInfo per usare gli elementi di testo anziché i singoli oggetti Char. Nell'esempio seguente viene utilizzato l'oggetto StringInfo per contare il numero di elementi di testo in una stringa costituita dai numeri dell'Mar Egeo da zero a nove. Poiché considera una coppia di surrogati un singolo carattere, segnala correttamente che la stringa contiene dieci caratteri.

  using System;
  using System.Globalization;
  
  public class Example4
  {
      public static void Main()
      {
          string result = String.Empty;
          for (int ctr = 0x10107; ctr <= 0x10110; ctr++)  // Range of Aegean numbers.
              result += Char.ConvertFromUtf32(ctr);
  
          StringInfo si = new StringInfo(result);
          Console.WriteLine($"The string contains {si.LengthInTextElements} characters.");
      }
  }
  // The example displays the following output:
  //       The string contains 10 characters.
  

  open System
  open System.Globalization
  
  let result =
      [ for i in 0x10107..0x10110 do  // Range of Aegean numbers.
          Char.ConvertFromUtf32 i ]
      |> String.concat ""
  
  
  let si = StringInfo result
  printfn $"The string contains {si.LengthInTextElements} characters."
  
  // The example displays the following output:
  //       The string contains 10 characters.
  

  Imports System.Globalization
  
  Module Example6
      Public Sub Main()
          Dim result As String = String.Empty
          For ctr As Integer = &H10107 To &H10110     ' Range of Aegean numbers.
              result += Char.ConvertFromUtf32(ctr)
          Next
          Dim si As New StringInfo(result)
          Console.WriteLine("The string contains {0} characters.", si.LengthInTextElements)
      End Sub
  End Module
  ' The example displays the following output:
  '       The string contains 10 characters.
  

• Se una stringa contiene un carattere di base con uno o più caratteri combinati, è possibile chiamare il metodo String.Normalize per convertire la sottostringa in una singola unità di codice con codifica UTF-16. Nell'esempio seguente viene chiamato il metodo String.Normalize per convertire il carattere base U+0061 (LETTERA MINUSCOLA LATINA A) e il carattere combinato U+0308 (DIAERESI COMBINATA) in U+00E4 (LETTERA MINUSCOLA LATINA A CON DIAERESI).

  using System;
  
  public class Example2
  {
      public static void Main()
      {
          string combining = "\u0061\u0308";
          ShowString(combining);
  
          string normalized = combining.Normalize();
          ShowString(normalized);
      }
  
      private static void ShowString(string s)
      {
          Console.Write($"Length of string: {s.Length} (");
          for (int ctr = 0; ctr < s.Length; ctr++)
          {
              Console.Write($"U+{Convert.ToUInt16(s[ctr]):X4}");
              if (ctr != s.Length - 1) Console.Write(" ");
          }
          Console.WriteLine(")\n");
      }
  }
  // The example displays the following output:
  //       Length of string: 2 (U+0061 U+0308)
  //
  //       Length of string: 1 (U+00E4)
  

  open System
  
  let showString (s: string) =
      printf $"Length of string: {s.Length} ("
      for i = 0 to s.Length - 1 do
          printf $"U+{Convert.ToUInt16 s[i]:X4}"
          if i <> s.Length - 1 then printf " "
      printfn ")\n"
  
  let combining = "\u0061\u0308"
  showString combining
  
  let normalized = combining.Normalize()
  showString normalized
  
  // The example displays the following output:
  //       Length of string: 2 (U+0061 U+0308)
  //
  //       Length of string: 1 (U+00E4)
  

  Module Example3
      Public Sub Main()
          Dim combining As String = ChrW(&H61) + ChrW(&H308)
          ShowString(combining)
  
          Dim normalized As String = combining.Normalize()
          ShowString(normalized)
      End Sub
  
      Private Sub ShowString(s As String)
          Console.Write("Length of string: {0} (", s.Length)
          For ctr As Integer = 0 To s.Length - 1
              Console.Write("U+{0:X4}", Convert.ToUInt16(s(ctr)))
              If ctr <> s.Length - 1 Then Console.Write(" ")
          Next
          Console.WriteLine(")")
          Console.WriteLine()
      End Sub
  End Module
  ' The example displays the following output:
  '       Length of string: 2 (U+0061 U+0308)
  '       
  '       Length of string: 1 (U+00E4)
  

Operazioni comuni

La struttura Char fornisce metodi per confrontare Char oggetti, convertire il valore dell'oggetto Char corrente in un oggetto di un altro tipo e determinare la categoria Unicode di un oggetto Char:

Valori di 'char' e interoperabilità

Quando un tipo di Char gestito, rappresentato come unità di codice con codifica UTF-16 Unicode, viene passato al codice non gestito, il marshaller di interoperabilità converte il set di caratteri in ANSI per impostazione predefinita. È possibile applicare l'attributo DllImportAttribute alle dichiarazioni platform invoke e all'attributo StructLayoutAttribute a una dichiarazione di interoperabilità COM per controllare il set di caratteri utilizzato da un tipo di Char sottoposto a marshalling.

Thread safety

Tutti i membri di questo tipo sono thread-safe. I membri che sembrano modificare lo stato dell'istanza restituiscono effettivamente una nuova istanza inizializzata con il nuovo valore. Come per qualsiasi altro tipo, la lettura e la scrittura in una variabile condivisa contenente un'istanza di questo tipo devono essere protette da un blocco per garantire la thread safety.

Vedi anche

• IComparable
• IConvertible
• String