Interface

# Readable

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Reading

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## Description

Provides "specs" for reading with the <span class="title-ref">Readable</span> class interface.

## Methods

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| Name                            | Parameters                                                                                                                               | Returns                            | Shared |
|---------------------------------|------------------------------------------------------------------------------------------------------------------------------------------|------------------------------------|--------|
| `EndOfFile<readable.endoffile>` |                                                                                                                                          | `Boolean</api/data_types/boolean>` |        |
| `Read<readable.read>`           | Count As `Integer</api/data_types/integer>`, encoding As `TextEncoding</api/text/encoding_text/textencoding>` = `Nil</api/language/nil>` | `String</api/data_types/string>`   |        |
| `ReadError<readable.readerror>` |                                                                                                                                          | `Boolean</api/data_types/boolean>` |        |

## Method descriptions

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Readable.EndOfFile

**EndOfFile** As `Boolean</api/data_types/boolean>`

> Returns `True</api/language/true>` when there's no more data left to read.
>
> This code reads the rows and columns of data from a tab-delimited text file into a `ListBox</api/user_interface/desktop/desktoplistbox>`:
>
> ``` xojo
> Var f As FolderItem
> Var textInput As TextInputStream
> Var rowFromFile As String
>
> f = FolderItem.ShowOpenFileDialog("text/plain") ' defined as a FileType
> If f <> Nil Then
>   textInput = TextInputStream.Open(f)
>   textInput.Encoding = Encodings.UTF8
>
>   Do
>     rowFromFile = textInput.ReadLine
>     Var values() As String = rowFromFile.ToArray(String.Chr(9))
>     ListBox1.ColumnCount = values.Count
>     ListBox1.AddRow("")
>     Var col As Integer
>     For Each value As String In values
>       ListBox1.CellTextAt(ListBox1.LastAddedRowIndex, col) = value
>       col = col + 1
>     Next
>   Loop Until textInput.EndOfFile
>
>   textInput.Close
> End If
> ```
>
> This example reads each pair of bytes from a file and writes them in reverse order to a new file. The user chooses the source file using the Open-file dialog box and saves the new file using the Save as dialog box. The EOF property is used to terminate the `Do...Loop</api/language/loops/do...loop>`.
>
> ``` xojo
> Var readFile As FolderItem = FolderItem.ShowOpenFileDialog("text")
> If readFile <> Nil Then
>   Var ReadStream As BinaryStream = BinaryStream.Open(readFile, False)
>   ReadStream.LittleEndian = True
>   Var writeFile As FolderItem = FolderItem.ShowSaveFileDialog("", "")
>   If writeFile <> Nil Then
>     Var writeStream As BinaryStream = BinaryStream.Create(writeFile, True)
>     writeStream.LittleEndian = True
>     Do Until ReadStream.EndOfFile
>       writeStream.WriteInt8(ReadStream.ReadInt8)
>     Loop
>     writeStream = Nil
>   End If
>   readStream = Nil
> End If
> ```

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Readable.Read

**Read**(Count As `Integer</api/data_types/integer>`, encoding As `TextEncoding</api/text/encoding_text/textencoding>` = `Nil</api/language/nil>`) As `String</api/data_types/string>`

> Reads *Count* bytes from the input stream and returns a `String</api/data_types/string>`.
>
> If provided, the optional parameter *encoding* specifies the text encoding to be defined for the `String</api/data_types/string>` to be read.
>
> If *Count* is higher than the amount of bytes currently available in the stream, all available bytes will be returned. Therefore, make sure to always consider the case that you get less than you requested. To see if you received all requested bytes, check the returned string's `String<string.bytes>` property (avoid using `Length<binarystream.length>` as it may give a different number if the encoding is not nil).
>
> If not enough memory is available, you get back an empty string.
>
> This example reads the first 1000 bytes from a `BinaryStream</api/files/binarystream>`.
>
> ``` xojo
> Var readFile As FolderItem = FolderItem.ShowOpenFileDialog("text/plain")
> If readFile <> Nil Then
>   Var ReadStream As BinaryStream = BinaryStream.Open(readFile, False)
>   ReadStream.LittleEndian = True
>   TextArea1.Text = ReadStream.Read(1000, Encodings.UTF8)
> End If
> ```

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Readable.ReadError

**ReadError** As `Boolean</api/data_types/boolean>`

> If `True</api/language/true>` then an error occurred during reading.

## Notes

The `BinaryStream</api/files/binarystream>`, `IPCSocket</api/networking/ipcsocket>`, `Pop3SecureSocket</api/networking/pop3securesocket>`, `SMTPSecureSocket</api/networking/smtpsecuresocket>`, `SSLSocket</api/networking/sslsocket>`, `SerialConnection</api/hardware/serialconnection>`, `TCPSocket</api/networking/tcpsocket>`, and `TextInputStream</api/files/textinputstream>` provide the <span class="title-ref">Readable</span> class interface. If you implement this class interface in your application, you must provide the methods with the parameters as shown here.

If an error occurs while reading, a `RuntimeException</api/exceptions/runtimeexception>` will occur.

## Compatibility

|                       |     |
|-----------------------|-----|
| **Project Types**     | All |
| **Operating Systems** | All |

<div class="seealso">

`BinaryStream</api/files/binarystream>`, `IPCSocket</api/networking/ipcsocket>`, `SerialConnection</api/hardware/serialconnection>`, `StdIn</api/console/stdin>`, `TCPSocket</api/networking/tcpsocket>`, `TextInputStream</api/files/textinputstream>` classes, `Writeable</api/files/writeable>` interface.

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