Process.StandardInput Property

Definition

Namespace:

System.Diagnostics

Assembly:

System.Diagnostics.Process.dll

Source:

Process.cs

Gets a stream used to write the input of the application.

public:
 property System::IO::StreamWriter ^ StandardInput { System::IO::StreamWriter ^ get(); };

public System.IO.StreamWriter StandardInput { get; }

member this.StandardInput : System.IO.StreamWriter

Public ReadOnly Property StandardInput As StreamWriter

Property Value

StreamWriter

A StreamWriter that can be used to write the standard input stream of the application.

Exceptions

InvalidOperationException

The StandardInput stream has not been defined because RedirectStandardInput is set to false.

Examples

The following example illustrates how to redirect the StandardInput stream of a process. The example starts the sort command with redirected input. It then prompts the user for text, and passes that to the sort process by means of the redirected StandardInput stream. The sort results are displayed to the user on the console.

#using <System.dll>

using namespace System;
using namespace System::IO;
using namespace System::Diagnostics;
using namespace System::ComponentModel;
int main()
{
   Console::WriteLine(  "Ready to sort one or more text lines..." );
   
   // Start the Sort.exe process with redirected input.
   // Use the sort command to sort the input text.
   Process^ myProcess = gcnew Process;
   if ( myProcess )
   {
      myProcess->StartInfo->FileName =  "Sort.exe";
      myProcess->StartInfo->UseShellExecute = false;
      myProcess->StartInfo->RedirectStandardInput = true;
      myProcess->Start();
      StreamWriter^ myStreamWriter = myProcess->StandardInput;
      if ( myStreamWriter )
      {
         
         // Prompt the user for input text lines to sort. 
         // Write each line to the StandardInput stream of
         // the sort command.
         String^ inputText;
         int numLines = 0;
         do
         {
            Console::WriteLine(  "Enter a line of text (or press the Enter key to stop):" );
            inputText = Console::ReadLine();
            if ( inputText && inputText->Length > 0 )
            {
               numLines++;
               myStreamWriter->WriteLine( inputText );
            }
         }
         while ( inputText && inputText->Length != 0 );
         
         // Write a report header to the console.
         if ( numLines > 0 )
         {
            Console::WriteLine(  " {0} sorted text line(s) ", numLines.ToString() );
            Console::WriteLine(  "------------------------" );
         }
         else
         {
            Console::WriteLine(  " No input was sorted" );
         }
         
         // End the input stream to the sort command.
         // When the stream closes, the sort command
         // writes the sorted text lines to the 
         // console.
         myStreamWriter->Close();
      }
      
      // Wait for the sort process to write the sorted text lines.
      myProcess->WaitForExit();
      myProcess->Close();
   }
}

using System;
using System.IO;
using System.Diagnostics;
using System.ComponentModel;

namespace ProcessStandardInputSample
{
    class StandardInputTest
    {
        static void Main()
        {
            Console.WriteLine("Ready to sort one or more text lines...");

            // Start the Sort.exe process with redirected input.
            // Use the sort command to sort the input text.
            using (Process myProcess = new Process())
            {
                myProcess.StartInfo.FileName = "Sort.exe";
                myProcess.StartInfo.UseShellExecute = false;
                myProcess.StartInfo.RedirectStandardInput = true;

                myProcess.Start();

                StreamWriter myStreamWriter = myProcess.StandardInput;

                // Prompt the user for input text lines to sort.
                // Write each line to the StandardInput stream of
                // the sort command.
                String inputText;
                int numLines = 0;
                do
                {
                    Console.WriteLine("Enter a line of text (or press the Enter key to stop):");

                    inputText = Console.ReadLine();
                    if (inputText.Length > 0)
                    {
                        numLines++;
                        myStreamWriter.WriteLine(inputText);
                    }
                } while (inputText.Length > 0);

                // Write a report header to the console.
                if (numLines > 0)
                {
                    Console.WriteLine($" {numLines} sorted text line(s) ");
                    Console.WriteLine("------------------------");
                }
                else
                {
                    Console.WriteLine(" No input was sorted");
                }

                // End the input stream to the sort command.
                // When the stream closes, the sort command
                // writes the sorted text lines to the
                // console.
                myStreamWriter.Close();

                // Wait for the sort process to write the sorted text lines.
                myProcess.WaitForExit();
            }
        }
    }
}

open System.Diagnostics

printfn "Ready to sort one or more text lines..."

// Start the Sort.exe process with redirected input.
// Use the sort command to sort the input text.
use myProcess = new Process()

myProcess.StartInfo.FileName <- "Sort.exe"
myProcess.StartInfo.UseShellExecute <- false
myProcess.StartInfo.RedirectStandardInput <- true

myProcess.Start() |> ignore

let myStreamWriter = myProcess.StandardInput

// Prompt the user for input text lines to sort.
// Write each line to the StandardInput stream of
// the sort command.

let mutable inputText = ""
let mutable numLines = 0

while inputText.Length > 0 do
    printfn "Enter a line of text (or press the Enter key to stop):"

    inputText <- stdin.ReadLine()

    if inputText.Length > 0 then
        numLines <- numLines + 1
        myStreamWriter.WriteLine inputText

// Write a report header to the console.
if numLines > 0 then
    printfn $" {numLines} sorted text line(s) "
    printfn "------------------------"
else
    printfn $" No input was sorted"

// End the input stream to the sort command.
// When the stream closes, the sort command
// writes the sorted text lines to the
// console.
myStreamWriter.Close()

// Wait for the sort process to write the sorted text lines.
myProcess.WaitForExit()

Imports System.IO
Imports System.Diagnostics
Imports System.ComponentModel

Namespace Process_StandardInput_Sample

    Class StandardInputTest

        Shared Sub Main()

            Console.WriteLine("Ready to sort one or more text lines...")

            ' Start the Sort.exe process with redirected input.
            ' Use the sort command to sort the input text.
            Using myProcess As New Process()

                myProcess.StartInfo.FileName = "Sort.exe"
                myProcess.StartInfo.UseShellExecute = False
                myProcess.StartInfo.RedirectStandardInput = True

                myProcess.Start()

                Dim myStreamWriter As StreamWriter = myProcess.StandardInput

                ' Prompt the user for input text lines to sort. 
                ' Write each line to the StandardInput stream of
                ' the sort command.
                Dim inputText As String
                Dim numLines As Integer = 0
                Do
                    Console.WriteLine("Enter a line of text (or press the Enter key to stop):")

                    inputText = Console.ReadLine()
                    If inputText.Length > 0 Then
                        numLines += 1
                        myStreamWriter.WriteLine(inputText)
                    End If
                Loop While inputText.Length <> 0


                ' Write a report header to the console.
                If numLines > 0 Then
                    Console.WriteLine($" {numLines} sorted text line(s) ")
                    Console.WriteLine("------------------------")
                Else
                    Console.WriteLine(" No input was sorted")
                End If

                ' End the input stream to the sort command.
                ' When the stream closes, the sort command
                ' writes the sorted text lines to the 
                ' console.
                myStreamWriter.Close()


                ' Wait for the sort process to write the sorted text lines.
                myProcess.WaitForExit()
            End Using

        End Sub
    End Class  'StandardInputTest
End Namespace 'Process_StandardInput_Sample

Remarks

A Process can read input text from its standard input stream, typically the keyboard. By redirecting the StandardInput stream, you can programmatically specify the input. For example, instead of using keyboard input, you can provide text from the contents of a designated file or output from another application.

Note

To use StandardInput, you must set ProcessStartInfo.UseShellExecute to false, and you must set ProcessStartInfo.RedirectStandardInput to true. Otherwise, writing to the StandardInput stream throws an exception.

See also

• StandardOutput
• StandardError
• RedirectStandardInput