Procedura: leggere caratteri da una stringa
Il codice dell'esempio che segue consente di leggere un determinato numero di caratteri da una stringa, a partire da un punto specifico. A tale scopo, viene utilizzato StringReader.
Il codice consente di definire una stringa e di convertirla in una matrice di caratteri, che può essere letta utilizzando il metodo StringReader.Read appropriato.
In questo esempio dalla stringa viene letto solo il numero di caratteri specificato, come indicato di seguito.
Esempio
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
Vedere anche
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Procedura: scrivere caratteri in una stringa