Console.Error Eigenschap

public:
 static property System::IO::TextWriter ^ Error { System::IO::TextWriter ^ get(); };

public static System.IO.TextWriter Error { get; }

static member Error : System.IO.TextWriter

Public Shared ReadOnly Property Error As TextWriter

Waarde van eigenschap

Een TextWriter die de standaardstroom voor foutuitvoer vertegenwoordigt.

Voorbeelden

Het volgende voorbeeld is een opdrachtregelprogramma met de naam ExpandTabs dat tabtekens in een tekstbestand vervangt door vier spaties, de waarde die is gedefinieerd door de tabSize variabele. Hiermee worden de standaardinvoer- en uitvoerstromen omgeleid naar bestanden, maar wordt de Error eigenschap gebruikt om de standaardfoutstroom naar de console te schrijven. Het kan worden gestart vanaf de opdrachtregel door de naam op te geven van het bestand dat tabtekens en de naam van het uitvoerbestand bevat.

using System;
using System.IO;

public class ExpandTabs
{
    private const int tabSize = 4;
    private const string usageText = "Usage: EXPANDTABSEX inputfile.txt outputfile.txt";

    public static void Main(string[] args)
    {
        StreamWriter writer = null;

        if (args.Length < 2) {
            Console.WriteLine(usageText);
            return;
        }

        try {
            writer = new StreamWriter(args[1]);
            Console.SetOut(writer);
            Console.SetIn(new StreamReader(args[0]));
        }
        catch(IOException e) {
            TextWriter errorWriter = Console.Error;
            errorWriter.WriteLine(e.Message);
            errorWriter.WriteLine(usageText);
            return;
        }
        int i;
        while ((i = Console.Read()) != -1) {
            char c = (char)i;
            if (c == '\t')
                Console.Write(("").PadRight(tabSize, ' '));
            else
                Console.Write(c);
        }
        writer.Close();
        // Recover the standard output stream so that a
        // completion message can be displayed.
        StreamWriter standardOutput = new StreamWriter(Console.OpenStandardOutput());
        standardOutput.AutoFlush = true;
        Console.SetOut(standardOutput);
        Console.WriteLine("EXPANDTABSEX has completed the processing of {0}.", args[0]);
        return;
    }
}

open System
open System.IO

let tabSize = 4
let usageText = "Usage: EXPANDTABSEX inputfile.txt outputfile.txt"

[<EntryPoint>]
let main args =
    if args.Length < 2 then
        printfn $"{usageText}"
    else 
        try
            use writer = new StreamWriter(args[1])
            Console.SetOut writer
            Console.SetIn(new StreamReader(args[0]))
            let mutable i = Console.Read()
            while i <> -1 do
                let c = char i
                if c = '\t' then
                    Console.WriteLine(("").PadRight(tabSize, ' '))
                else
                    printf $"{c}"
                i <- Console.Read()
            // Recover the standard output stream so that a
            // completion message can be displayed.
            use standardOutput = new StreamWriter(Console.OpenStandardOutput())
            standardOutput.AutoFlush <- true
            Console.SetOut standardOutput
            printfn $"EXPANDTABSEX has completed the processing of {args[0]}."
        with :? IOException as e ->
            let errorWriter = Console.Error
            errorWriter.WriteLine e.Message
            errorWriter.WriteLine usageText
    0

Imports System.IO

Public Class ExpandTabs
   Private Const tabSize As Integer = 4
   Private Const usageText As String = "Usage: EXPANDTABSEX inputfile.txt outputfile.txt"
   
   Public Shared Sub Main(args() As String)
      Dim writer As StreamWriter = Nothing

      If args.Length < 2 Then
         Console.WriteLine(usageText)
         Exit Sub
      End If
      
      Try
         writer = New StreamWriter(args(1))
         Console.SetOut(writer)
         Console.SetIn(New StreamReader(args(0)))
      Catch e As IOException
         Console.Error.WriteLine(e.Message)
         Console.Error.WriteLine(usageText)
         Exit Sub
      End Try
      
      Dim i As Integer = Console.Read()
      While i <> -1 
         Dim c As Char = Convert.ToChar(i)
         If c = ControlChars.Tab Then
            Console.Write("".PadRight(tabSize, " "c))
         Else
            Console.Write(c)
         End If
         i = Console.Read()
      End While
      writer.Close()
      
      ' Reacquire the standard output stream so that a
      ' completion message can be displayed.
      Dim standardOutput As New StreamWriter(Console.OpenStandardOutput)
      standardOutput.AutoFlush = True
      Console.SetOut(standardOutput)
      Console.WriteLine("EXPANDTABSEX has completed the processing of {0}.", args(0))
   End Sub
End Class

Het volgende voorbeeld is een eenvoudige viewer voor tekstbestanden waarmee de inhoud van een of meer tekstbestanden naar de console wordt weergegeven. Als er geen opdrachtregelargumenten zijn of als bestanden die als opdrachtregelargumenten worden doorgegeven niet bestaan, roept het voorbeeld de SetError methode aan om foutgegevens om te leiden naar een bestand, roept de OpenStandardError methode aan tijdens het opnieuw aanvragen van de standaardfoutstroom en geeft aan dat foutinformatie naar een bestand is geschreven.

using System;
using System.IO;

public class ViewTextFile
{
   public static void Main()
   {
      String[] args = Environment.GetCommandLineArgs();
      String errorOutput = "";
      // Make sure that there is at least one command line argument.
      if (args.Length <= 1)
         errorOutput += "You must include a filename on the command line.\n";

      for (int ctr = 1; ctr <= args.GetUpperBound(0); ctr++)  {
         // Check whether the file exists.
         if (!File.Exists(args[ctr])) {
            errorOutput += String.Format("'{0}' does not exist.\n", args[ctr]);
         }
         else {
            // Display the contents of the file.
            StreamReader sr = new StreamReader(args[ctr]);
            String contents = sr.ReadToEnd();
            sr.Close();
            Console.WriteLine("*****Contents of file '{0}':\n\n",
                              args[ctr]);
            Console.WriteLine(contents);
            Console.WriteLine("*****\n");
         }
      }

      // Check for error conditions.
      if (!String.IsNullOrEmpty(errorOutput)) {
         // Write error information to a file.
         Console.SetError(new StreamWriter(@".\ViewTextFile.Err.txt"));
         Console.Error.WriteLine(errorOutput);
         Console.Error.Close();
         // Reacquire the standard error stream.
         var standardError = new StreamWriter(Console.OpenStandardError());
         standardError.AutoFlush = true;
         Console.SetError(standardError);
         Console.Error.WriteLine("\nError information written to ViewTextFile.Err.txt");
      }
   }
}
// If the example is compiled and run with the following command line:
//     ViewTextFile file1.txt file2.txt
// and neither file1.txt nor file2.txt exist, it displays the
// following output:
//     Error information written to ViewTextFile.Err.txt
// and writes the following text to ViewTextFile.Err.txt:
//     'file1.txt' does not exist.
//     'file2.txt' does not exist.

open System
open System.IO

let args = Environment.GetCommandLineArgs()[1..]
let mutable errorOutput = ""
// Make sure that there is at least one command line argument.
if args.Length < 1 then
    errorOutput <- errorOutput + "You must include a filename on the command line.\n"

for file in args do
    // Check whether the file exists.
    if File.Exists file then
        errorOutput <- errorOutput + $"'{file}' does not exist.\n"
    else
        // Display the contents of the file.
        use sr = new StreamReader(file)
        let contents = sr.ReadToEnd()
        Console.WriteLine $"*****Contents of file '{file}':\n\n"
        Console.WriteLine contents
        Console.WriteLine "*****\n"

// Check for error conditions.
if not (String.IsNullOrEmpty errorOutput) then
    // Write error information to a file.
    Console.SetError(new StreamWriter(@".\ViewTextFile.Err.txt"))
    Console.Error.WriteLine errorOutput
    Console.Error.Close()
    // Reacquire the standard error stream.
    use standardError = new StreamWriter(Console.OpenStandardError())
    standardError.AutoFlush <- true
    Console.SetError standardError
    Console.Error.WriteLine "\nError information written to ViewTextFile.Err.txt"

// If the example is compiled and run with the following command line:
//     ViewTextFile file1.txt file2.txt
// and neither file1.txt nor file2.txt exist, it displays the
// following output:
//     Error information written to ViewTextFile.Err.txt
// and writes the following text to ViewTextFile.Err.txt:
//     'file1.txt' does not exist.
//     'file2.txt' does not exist.

Imports System.IO

Module ViewTextFile
   Public Sub Main()
      Dim args() As String = Environment.GetCommandLineArgs()
      Dim errorOutput As String = ""
      ' Make sure that there is at least one command line argument.
      If args.Length <= 1 Then
         errorOutput += "You must include a filename on the command line." +
                        vbCrLf
      End If
      
      For ctr As Integer = 1 To args.GetUpperBound(0)
         ' Check whether the file exists.
         If Not File.Exists(args(ctr)) Then
            errorOutput += String.Format("'{0}' does not exist.{1}",
                                         args(ctr), vbCrLf)
         Else
            ' Display the contents of the file.
            Dim sr As New StreamReader(args(ctr))
            Dim contents As String = sr.ReadToEnd()
            sr.Close()
            Console.WriteLine("***** Contents of file '{0}':{1}{1}",
                              args(ctr), vbCrLf)
            Console.WriteLine(contents)
            Console.WriteLine("*****{0}", vbCrLf)
         End If
      Next

      ' Check for error conditions.
      If Not String.IsNullOrEmpty(errorOutput) Then
         ' Write error information to a file.
         Console.SetError(New StreamWriter(".\ViewTextFile.Err.txt"))
         Console.Error.WriteLine(errorOutput)
         Console.Error.Close()
         ' Reacquire the standard error stream.
         Dim standardError As New StreamWriter(Console.OpenStandardError())
         standardError.AutoFlush = True
         Console.SetError(standardError)
         Console.Error.WriteLine("{0}Error information written to ViewTextFile.Err.txt",
                                 vbCrLf)
      End If
   End Sub
End Module
' If the example is compiled and run with the following command line:
'     ViewTextFile file1.txt file2.txt
' and neither file1.txt nor file2.txt exist, it displays the
' following output:
'     Error information written to ViewTextFile.Err.txt
' and writes the following text to ViewTextFile.Err.txt:
'     'file1.txt' does not exist.
'     'file2.txt' does not exist.

Houd er rekening mee dat de StreamWriter.AutoFlush eigenschap is ingesteld true op voordat de foutstroom opnieuw wordt geactiveerd. Dit zorgt ervoor dat uitvoer onmiddellijk naar de console wordt verzonden in plaats van gebufferd.

Opmerkingen

Deze standaardfoutstroom is standaard ingesteld op de console. Deze kan worden ingesteld op een andere stream met de SetError methode. Nadat de standaardfoutstroom is omgeleid, kan deze opnieuw worden opgehaald door de OpenStandardError methode aan te roepen.

In consoletoepassingen waarvan de informatieve uitvoer vaak wordt omgeleid naar een bestand, kan de standaardfoutstroom die beschikbaar is via de Error eigenschap, worden gebruikt om informatie weer te geven aan de console, zelfs als uitvoer wordt omgeleid. In het volgende voorbeeld worden producttabellen weergegeven voor 10 getallen tegelijk, te beginnen met 1. Na elke set van 10 getallen wordt de Error eigenschap gebruikt om de gebruiker te vragen of de volgende set moet worden weergegeven. Als de standaarduitvoer wordt omgeleid naar een bestand, wordt de gebruiker nog steeds gevraagd of de routine de volgende set producten moet genereren.

using System;

public class Example
{
   public static void Main()
   {
      int increment = 0;
      bool exitFlag = false;

      while (!exitFlag) {
         if (Console.IsOutputRedirected)
            Console.Error.WriteLine("Generating multiples of numbers from {0} to {1}",
                                    increment + 1, increment + 10);

         Console.WriteLine("Generating multiples of numbers from {0} to {1}",
                           increment + 1, increment + 10);
         for (int ctr = increment + 1; ctr <= increment + 10; ctr++) {
            Console.Write("Multiples of {0}: ", ctr);
            for (int ctr2 = 1; ctr2 <= 10; ctr2++)
               Console.Write("{0}{1}", ctr * ctr2, ctr2 == 10 ? "" : ", ");

            Console.WriteLine();
         }
         Console.WriteLine();

         increment += 10;
         Console.Error.Write("Display multiples of {0} through {1} (y/n)? ",
                             increment + 1, increment + 10);
         Char response = Console.ReadKey(true).KeyChar;
         Console.Error.WriteLine(response);
         if (!Console.IsOutputRedirected)
            Console.CursorTop--;

         if (Char.ToUpperInvariant(response) == 'N')
            exitFlag = true;
      }
   }
}

open System

let mutable increment = 0
let mutable exitFlag = false

while not exitFlag do
    if Console.IsOutputRedirected then
        Console.Error.WriteLine $"Generating multiples of numbers from {increment + 1} to {increment + 10}"

    Console.WriteLine $"Generating multiples of numbers from {increment + 1} to {increment + 10}"

    for i = increment + 1 to increment + 10 do
        Console.Write $"Multiples of {i}: "
        for j = 1 to 10 do
            Console.Write $"""{i * j}{if j = 10 then "" else ", "}"""

        Console.WriteLine()
    Console.WriteLine()

    increment <- increment + 10
    Console.Error.Write $"Display multiples of {increment + 1} through {increment + 10} (y/n)? "
    let response = Console.ReadKey(true).KeyChar
    Console.Error.WriteLine response
    if not Console.IsOutputRedirected then
        Console.CursorTop <- Console.CursorTop - 1 

    if Char.ToUpperInvariant response = 'N' then
        exitFlag <- true

Module Example
   Public Sub Main()
      Dim increment As Integer = 0
      Dim exitFlag As Boolean = False
      
      Do While Not exitFlag
         If Console.IsOutputRedirected Then
            Console.Error.WriteLine("Generating multiples of numbers from {0} to {1}",
                                    increment + 1, increment + 10)
         End If
         Console.WriteLine("Generating multiples of numbers from {0} to {1}",
                           increment + 1, increment + 10)
         For ctr As Integer = increment + 1 To increment + 10
            Console.Write("Multiples of {0}: ", ctr)
            For ctr2 As Integer = 1 To 10
               Console.Write("{0}{1}", ctr * ctr2, If(ctr2 = 10, "", ", "))
            Next
            Console.WriteLine()
         Next
         Console.WriteLine()
         
         increment += 10
         Console.Error.Write("Display multiples of {0} through {1} (y/n)? ",
                             increment + 1, increment + 10)
         Dim response As Char = Console.ReadKey(True).KeyChar
         Console.Error.WriteLine(response)
         If Not Console.IsOutputRedirected Then
            Console.CursorTop = Console.CursorTop - 1
         End If
         If Char.ToUpperInvariant(response) = "N" Then exitFlag = True
      Loop
   End Sub
End Module

Zie ook

• In
• Out
• IsErrorRedirected
• SetError(TextWriter)