Console.Read Method

Reference

Definition

Namespace:: System

Assembly:: System.Console.dll

Assembly:: mscorlib.dll

Assembly:: netstandard.dll

Source:: Console.cs

Source:: Console.cs

Source:: Console.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Reads the next character from the standard input stream.

public:
 static int Read();

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
public static int Read ();

[System.Runtime.Versioning.UnsupportedOSPlatform("browser")]
[System.Runtime.Versioning.UnsupportedOSPlatform("android")]
public static int Read ();

public static int Read ();

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
static member Read : unit -> int

[<System.Runtime.Versioning.UnsupportedOSPlatform("browser")>]
[<System.Runtime.Versioning.UnsupportedOSPlatform("android")>]
static member Read : unit -> int

static member Read : unit -> int

Public Shared Function Read () As Integer

Returns

Int32

The next character from the input stream, or negative one (-1) if there are currently no more characters to be read.

Attributes: UnsupportedOSPlatformAttribute

Exceptions

IOException

An I/O error occurred.

Examples

The following example demonstrates the Read method.

// This example demonstrates the Console.Read() method.
using namespace System;
int main()
{
   String^ m1 = "\nType a string of text then press Enter. "
   "Type '+' anywhere in the text to quit:\n";
   String^ m2 = "Character '{0}' is hexadecimal 0x{1:x4}.";
   String^ m3 = "Character     is hexadecimal 0x{0:x4}.";
   Char ch;
   int x;
   
   //
   Console::WriteLine( m1 );
   do
   {
      x = Console::Read();
      try
      {
         ch = Convert::ToChar( x );
         if ( Char::IsWhiteSpace( ch ) )
         {
            Console::WriteLine( m3, x );
            if ( ch == 0x0a )
                        Console::WriteLine( m1 );
         }
         else
                  Console::WriteLine( m2, ch, x );
      }
      catch ( OverflowException^ e ) 
      {
         Console::WriteLine( "{0} Value read = {1}.", e->Message, x );
         ch = Char::MinValue;
         Console::WriteLine( m1 );
      }

   }
   while ( ch != '+' );
}

/*
This example produces the following results:

Type a string of text then press Enter. Type '+' anywhere in the text to quit:

The quick brown fox.
Character 'T' is hexadecimal 0x0054.
Character 'h' is hexadecimal 0x0068.
Character 'e' is hexadecimal 0x0065.
Character     is hexadecimal 0x0020.
Character 'q' is hexadecimal 0x0071.
Character 'u' is hexadecimal 0x0075.
Character 'i' is hexadecimal 0x0069.
Character 'c' is hexadecimal 0x0063.
Character 'k' is hexadecimal 0x006b.
Character     is hexadecimal 0x0020.
Character 'b' is hexadecimal 0x0062.
Character 'r' is hexadecimal 0x0072.
Character 'o' is hexadecimal 0x006f.
Character 'w' is hexadecimal 0x0077.
Character 'n' is hexadecimal 0x006e.
Character     is hexadecimal 0x0020.
Character 'f' is hexadecimal 0x0066.
Character 'o' is hexadecimal 0x006f.
Character 'x' is hexadecimal 0x0078.
Character '.' is hexadecimal 0x002e.
Character     is hexadecimal 0x000d.
Character     is hexadecimal 0x000a.

Type a string of text then press Enter. Type '+' anywhere in the text to quit:

^Z
Value was either too large or too small for a character. Value read = -1.

Type a string of text then press Enter. Type '+' anywhere in the text to quit:

+
Character '+' is hexadecimal 0x002b.

*/

// This example demonstrates the Console.Read() method.
using System;

class Sample
{
    public static void Main()
    {
    string m1 = "\nType a string of text then press Enter. " +
                "Type '+' anywhere in the text to quit:\n";
    string m2 = "Character '{0}' is hexadecimal 0x{1:x4}.";
    string m3 = "Character     is hexadecimal 0x{0:x4}.";
    char ch;
    int x;
//
    Console.WriteLine(m1);
    do
        {
        x = Console.Read();
        try
            {
            ch = Convert.ToChar(x);
            if (Char.IsWhiteSpace(ch))
               {
               Console.WriteLine(m3, x);
               if (ch == 0x0a)
                   Console.WriteLine(m1);
               }
            else
                {
                    Console.WriteLine(m2, ch, x);
                }
            }
        catch (OverflowException e)
            {
            Console.WriteLine("{0} Value read = {1}.", e.Message, x);
            ch = Char.MinValue;
            Console.WriteLine(m1);
            }
        } while (ch != '+');
    }
}
/*
This example produces the following results:

Type a string of text then press Enter. Type '+' anywhere in the text to quit:

The quick brown fox.
Character 'T' is hexadecimal 0x0054.
Character 'h' is hexadecimal 0x0068.
Character 'e' is hexadecimal 0x0065.
Character     is hexadecimal 0x0020.
Character 'q' is hexadecimal 0x0071.
Character 'u' is hexadecimal 0x0075.
Character 'i' is hexadecimal 0x0069.
Character 'c' is hexadecimal 0x0063.
Character 'k' is hexadecimal 0x006b.
Character     is hexadecimal 0x0020.
Character 'b' is hexadecimal 0x0062.
Character 'r' is hexadecimal 0x0072.
Character 'o' is hexadecimal 0x006f.
Character 'w' is hexadecimal 0x0077.
Character 'n' is hexadecimal 0x006e.
Character     is hexadecimal 0x0020.
Character 'f' is hexadecimal 0x0066.
Character 'o' is hexadecimal 0x006f.
Character 'x' is hexadecimal 0x0078.
Character '.' is hexadecimal 0x002e.
Character     is hexadecimal 0x000d.
Character     is hexadecimal 0x000a.

Type a string of text then press Enter. Type '+' anywhere in the text to quit:

^Z
Value was either too large or too small for a character. Value read = -1.

Type a string of text then press Enter. Type '+' anywhere in the text to quit:

+
Character '+' is hexadecimal 0x002b.

*/

// This example demonstrates the Console.Read() method.
open System

// string m2 = "Character '{0}' is hexadecimal 0x{1:x4}.";
// string m3 = "Character     is hexadecimal 0x{0:x4}.";
// char ch;

printfn "\nType a string of text then press Enter. Type '+' anywhere in the text to quit:\n"

let mutable ch = ' '
let mutable x = 0

while ch <> '+' do
    x <- Console.Read()
    try
        ch <- Convert.ToChar x
        if Char.IsWhiteSpace ch then
            printfn $"Character     is hexadecimal 0x{x:x4}."
            if ch = char '\u000A' then
                printfn "\nType a string of text then press Enter. Type '+' anywhere in the text to quit:\n"
        else
            printfn $"Character '{ch}' is hexadecimal 0x{x:x4}." 
    
    with :? OverflowException as e ->
        printfn $"{e.Message} Value read = {x}."
        ch <- Char.MinValue
        printfn "\nType a string of text then press Enter. Type '+' anywhere in the text to quit:\n"


// This example produces the following results:
//
// Type a string of text then press Enter. Type '+' anywhere in the text to quit:
//
// The quick brown fox.
// Character 'T' is hexadecimal 0x0054.
// Character 'h' is hexadecimal 0x0068.
// Character 'e' is hexadecimal 0x0065.
// Character     is hexadecimal 0x0020.
// Character 'q' is hexadecimal 0x0071.
// Character 'u' is hexadecimal 0x0075.
// Character 'i' is hexadecimal 0x0069.
// Character 'c' is hexadecimal 0x0063.
// Character 'k' is hexadecimal 0x006b.
// Character     is hexadecimal 0x0020.
// Character 'b' is hexadecimal 0x0062.
// Character 'r' is hexadecimal 0x0072.
// Character 'o' is hexadecimal 0x006f.
// Character 'w' is hexadecimal 0x0077.
// Character 'n' is hexadecimal 0x006e.
// Character     is hexadecimal 0x0020.
// Character 'f' is hexadecimal 0x0066.
// Character 'o' is hexadecimal 0x006f.
// Character 'x' is hexadecimal 0x0078.
// Character '.' is hexadecimal 0x002e.
// Character     is hexadecimal 0x000d.
// Character     is hexadecimal 0x000a.
//
// Type a string of text then press Enter. Type '+' anywhere in the text to quit:
//
// ^Z
// Value was either too large or too small for a character. Value read = -1.
//
// Type a string of text then press Enter. Type '+' anywhere in the text to quit:
//
// +
// Character '+' is hexadecimal 0x002b.

' This example demonstrates the Console.Read() method.
Class Sample
   Public Shared Sub Main()
      Dim m1 As String = _
                vbCrLf & _
                "Type a string of text then press Enter. " & _
                "Type '+' anywhere in the text to quit:" & _
                vbCrLf
      Dim m2 As String = "Character '{0}' is hexadecimal 0x{1:x4}."
      Dim m3 As String = "Character     is hexadecimal 0x{0:x4}."
      Dim ch As Char
      Dim x As Integer
      '
      Console.WriteLine(m1)
      Do
         x = Console.Read()
         Try
            ch = Convert.ToChar(x)
            If Char.IsWhiteSpace(ch) Then
               Console.WriteLine(m3, x)
               If ch = vbLf Then
                  Console.WriteLine(m1)
               End If
            Else
               Console.WriteLine(m2, ch, x)
            End If
         Catch e As OverflowException
            Console.WriteLine("{0} Value read = {1}.", e.Message, x)
            ch = Char.MinValue
            Console.WriteLine(m1)
         End Try
      Loop While ch <> "+"c
   End Sub
End Class
'
'This example produces the following results:
'
'Type a string of text then press Enter. Type '+' anywhere in the text to quit:
'
'The quick brown fox.
'Character 'T' is hexadecimal 0x0054.
'Character 'h' is hexadecimal 0x0068.
'Character 'e' is hexadecimal 0x0065.
'Character     is hexadecimal 0x0020.
'Character 'q' is hexadecimal 0x0071.
'Character 'u' is hexadecimal 0x0075.
'Character 'i' is hexadecimal 0x0069.
'Character 'c' is hexadecimal 0x0063.
'Character 'k' is hexadecimal 0x006b.
'Character     is hexadecimal 0x0020.
'Character 'b' is hexadecimal 0x0062.
'Character 'r' is hexadecimal 0x0072.
'Character 'o' is hexadecimal 0x006f.
'Character 'w' is hexadecimal 0x0077.
'Character 'n' is hexadecimal 0x006e.
'Character     is hexadecimal 0x0020.
'Character 'f' is hexadecimal 0x0066.
'Character 'o' is hexadecimal 0x006f.
'Character 'x' is hexadecimal 0x0078.
'Character '.' is hexadecimal 0x002e.
'Character     is hexadecimal 0x000d.
'Character     is hexadecimal 0x000a.
'
'Type a string of text then press Enter. Type '+' anywhere in the text to quit:
'
'^Z
'Value was either too large or too small for a character. Value read = -1.
'
'Type a string of text then press Enter. Type '+' anywhere in the text to quit:
'
'+
'Character '+' is hexadecimal 0x002b.
'

Remarks

The Read method blocks its return while you type input characters; it terminates when you press the Enter key. Pressing Enter appends a platform-dependent line termination sequence to your input (for example, Windows appends a carriage return-linefeed sequence). Subsequent calls to the Read method retrieve your input one character at a time. After the final character is retrieved, Read blocks its return again and the cycle repeats.

Important

The ReadLine method, or the KeyAvailable property and ReadKey method are preferable to using the Read method.

Note that the method does not return -1 unless you perform one of the following actions:

Simultaneously press the Control modifier key and Z console key (Ctrl+Z), which signals the end-of-file condition. If you're on Windows, you must also press the Enter console key.
Press an equivalent key that signals the end-of-file condition, such as the F6 function key in Windows.
Redirect the input stream to a source, such as a text file, that has an actual end-of-file character.

Applies to

Partajați prin