# Poco

# class FileIOS

Library: Foundation
Package: Streams
Header: Poco/FileStream.h

## Description

The base class for FileInputStream and FileOutputStream.

This class is needed to ensure the correct initialization order of the stream buffer and base classes.

Files are always opened in binary mode, a text mode with CR-LF translation is not supported. Thus, the file is always opened as if the std::ios::binary flag was specified. Use an InputLineEndingConverter or OutputLineEndingConverter if you require CR-LF translation.

On Windows platforms, UTF-8 encoded Unicode paths are correctly handled.

## Inheritance

Direct Base Classes: std::ios

All Base Classes: std::ios

Known Derived Classes: FileStream, FileInputStream, FileOutputStream

## Member Summary

Member Functions: close, flushToDisk, nativeHandle, open, openHandle, rdbuf, size

## Types Aliases

### NativeHandle

using NativeHandle = FileStreamBuf::NativeHandle;

## Constructors

### FileIOS

FileIOS();

Creates the basic stream.

## Destructor

### ~FileIOS

~FileIOS() override;

Destroys the stream.

## Member Functions

### close

void close();

Closes the file stream.

If, for an output stream, the close operation fails (because the contents of the stream buffer cannot synced back to the filesystem), the bad bit is set in the stream state.

### flushToDisk

void flushToDisk();

Forces buffered data to be written to the disk

### nativeHandle

NativeHandle nativeHandle() const;

Returns native file descriptor handle

### open

virtual void open(
const std::string & path,
std::ios::openmode mode
);

Opens the file specified by path, using the given mode.

Throws a FileException (or a similar exception) if the file does not exist or is not accessible for other reasons and a new file cannot be created.

### openHandle

void openHandle(
NativeHandle handle,
std::ios::openmode mode
);

Takes ownership of the handle.

### rdbuf

FileStreamBuf * rdbuf();

Returns a pointer to the underlying streambuf.

### size

UInt64 size() const;

Returns file size

## Variables

### _buf

FileStreamBuf _buf;