Comment : lire les caractères d'une chaîne

Article
08/10/2011

L'exemple de code suivant permet de lire un certain nombre de caractères à partir d'une chaîne existante, en commençant à un emplacement spécifié dans la chaîne. Utilisez StringReader à cette fin, comme illustré ci-dessous.

Ce code définit une chaîne et la convertit en tableau de caractères, qui peut alors être lu en utilisant la méthode StringReader.Read appropriée.

Cet exemple ne lit que le nombre caractères spécifié à partir de la chaîne, comme indiqué ci-après.

Exemple

Imports System
Imports System.IO

Public Class CharsFromStr
    Public Shared Sub Main()
        ' Create a string to read characters from.
        Dim str As String = "Some number of characters"
        ' Make a char array the size of the source string
        Dim b(str.Length) As Char
        ' Create an instance of StringReader and attach it to the string.
        Dim sr As New StringReader(str)
        ' Read 13 characters into the array that holds the string,
        ' starting at the third array member.
        sr.Read(b, 0, 13)
        ' Display the output.
        Console.WriteLine(b)
        ' Read the rest of the string from the current position in the
        ' source string into the array, starting at the 6th array member.
        sr.Read(b, 5, str.Length - 13)
        ' Display the output.
        Console.WriteLine(b)
        ' Close the StringReader.
        sr.Close()
    End Sub
End Class
' The example has the following output:
'
' Some number o
' Some f characters

using System;
using System.IO;

public class CharsFromStr
{
    public static void Main()
    {
        // Create a string to read characters from.
        string str = "Some number of characters";
        // Make a char array the size of the source string
        char[] b = new char[str.Length];
        // Create an instance of StringReader and attach it to the string.
        StringReader sr = new StringReader(str);
        // Read 13 characters into the array that holds the string,
        // starting at the third array member.
        sr.Read(b, 0, 13);
        // Display the output.
        Console.WriteLine(b);
        // Read the rest of the string from the current position in the
        // source string into the array, starting at the 6th array member.
        sr.Read(b, 5, str.Length - 13);
        // Display the output.
        Console.WriteLine(b);
        // Close the StringReader.
        sr.Close();
    }
}
// The example has the following output:
//
// Some number o
// Some f characters

using namespace System;
using namespace System::IO;

public ref class CharsFromStr
{
public:
    static void Main()
    {
        // Create a string to read characters from.
        String^ str = "Some number of characters";
        // Make a char array the size of the source string
        array<Char>^ b = gcnew array<Char>(str->Length);
        // Create an instance of StringReader and attach it to the string.
        StringReader^ sr = gcnew StringReader(str);
        // Read 13 characters into the array that holds the string,
        // starting at the third array member.
        sr->Read(b, 0, 13);
        // Display the output.
        Console::WriteLine(b);
        // Read the rest of the string from the current position in the
        // source string into the array, starting at the 6th array member.
        sr->Read(b, 5, str->Length - 13);
        // Display the output.
        Console::WriteLine(b);
        // Close the StringReader.
        sr->Close();
    }
};

int main()
{
    CharsFromStr::Main();
}
// The example has the following output:
//
// Some number o
// Some f characters

Comment : lire les caractères d'une chaîne

Exemple

Voir aussi

Tâches

Référence

Concepts

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