# wxStreamBase Class Reference
[Streams]

`#include </home/work/projects/wx/2.9/wx/interface/wx/stream.h>`

Inheritance diagram for wxStreamBase:
[legend]

## Detailed Description

This class is the base class of most stream related classes in wxWidgets.

It must not be used directly.

##

Library: wxBase
Category: Streams

See also:
  wxStreamBuffer

## Public Member Functions

| wxStreamBase ()
| Creates a dummy stream object.
virtual | ~wxStreamBase ()
| Destructor.
wxStreamError | GetLastError () const
| This function returns the last error.
virtual wxFileOffset | GetLength () const
| Returns the length of the stream in bytes.
virtual size_t | GetSize () const
| This function returns the size of the stream.
virtual bool | IsOk () const
| Returns true if no error occurred on the stream.
virtual bool | IsSeekable () const
| Returns true if the stream supports seeking to arbitrary offsets.
bool | operator! () const
| Returns the opposite of IsOk().

## Protected Member Functions

virtual wxFileOffset | OnSysSeek (wxFileOffset pos, wxSeekMode mode)
| Internal function.
virtual wxFileOffset | OnSysTell () const
| Internal function.

List of all members.

## Constructor & Destructor Documentation

wxStreamBase::wxStreamBase | ( |  | ) |

Creates a dummy stream object.

It doesn't do anything.

virtual wxStreamBase::~wxStreamBase | ( |  | ) | `[virtual]`

Destructor.

## Member Function Documentation

wxStreamError wxStreamBase::GetLastError | ( |  | ) | const

This function returns the last error.

virtual wxFileOffset wxStreamBase::GetLength | ( |  | ) | const`[virtual]`

Returns the length of the stream in bytes.

If the length cannot be determined (this is always the case for socket streams for example), returns wxInvalidOffset.

Since:
  2.5.4

virtual size_t wxStreamBase::GetSize | ( |  | ) | const`[virtual]`

This function returns the size of the stream.

For example, for a file it is the size of the file.

Warning:
  There are streams which do not have size by definition, such as socket streams. In that cases, GetSize() returns 0 so you should always test its return value.

Reimplemented in wxCountingOutputStream.

virtual bool wxStreamBase::IsOk | ( |  | ) | const`[virtual]`

Returns true if no error occurred on the stream.

See also:
  GetLastError()

Reimplemented in wxFFileOutputStream, wxFileOutputStream, wxFileInputStream, wxFFileInputStream, wxFFileStream, and wxFileStream.

virtual bool wxStreamBase::IsSeekable | ( |  | ) | const`[virtual]`

Returns true if the stream supports seeking to arbitrary offsets.

virtual wxFileOffset wxStreamBase::OnSysSeek | ( | wxFileOffset | pos,
|  | wxSeekMode | mode |
| ) |  |  | `[protected, virtual]`

Internal function.

It is called when the stream needs to change the current position.

Parameters:

  | pos | Offset to seek to.
  | mode | One of the wxSeekMode enumeration values.

Returns:
  The new stream position or wxInvalidOffset on error.

virtual wxFileOffset wxStreamBase::OnSysTell | ( |  | ) | const`[protected, virtual]`

Internal function.

It is called when the stream needs to know the real position.

Returns:
  The current stream position.

bool wxStreamBase::operator! | ( |  | ) | const

Returns the opposite of IsOk().

You can use this function to test the validity of the stream as if it was a pointer:

                bool DoSomething(wxInputStream& stream)
                {
                    wxInt32 data;
                    if (!stream.Read(&data, 4))
                        return false;
                    ...
                }

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