Reads count characters from the IO device, a whole :line or the whole device with :all.

It returns:

• data - the input characters

• :eof - end of file was encountered

• {:error, reason} - other (rare) error condition; for instance, {:error, :estale} if reading from an NFS volume

If :all is given, :eof is never returned, but an empty string in case the device has reached EOF.

Note: do not use this function on IO devices in unicode mode as it will return the wrong result.

Converts the IO device into a IO.Stream.

An IO.Stream implements both Enumerable and Collectable, allowing it to be used for both read and write.

The device is iterated line by line or by a number of bytes. This reads the IO device as a raw binary.

Note that an IO stream has side effects and every time you go over the stream you may get different results.

Finally, do not use this function on IO devices in unicode mode as it will return the wrong result.

Writes the given argument to the given device as a binary, no unicode conversion happens.

Check write/2 for more information.

Note: do not use this function on IO devices in unicode mode as it will return the wrong result.

Converts chardata (a list of integers representing codepoints, lists and strings) into a string.

In case the conversion fails, it raises a UnicodeConversionError. If a string is given, returns the string itself.

Examples

iex> IO.chardata_to_string([0x00E6, 0x00DF])
"æß"

iex> IO.chardata_to_string([0x0061, "bc"])
"abc"

Gets a number of bytes from the io device. If the io device is a unicode device, count implies the number of unicode codepoints to be retrieved. Otherwise, count is the number of raw bytes to be retrieved. It returns:

• data - the input characters

• :eof - end of file was encountered

• {:error, reason} - other (rare) error condition; for instance, {:error, :estale} if reading from an NFS volume

Gets a number of bytes from the io device. If the io device is a unicode device, count implies the number of unicode codepoints to be retrieved. Otherwise, count is the number of raw bytes to be retrieved.

Reads a line from the IO device. It returns:

• data - the characters in the line terminated by a LF (or end of file)

• :eof - end of file was encountered

• {:error, reason} - other (rare) error condition; for instance, {:error, :estale} if reading from an NFS volume

Inspects and writes the given argument to the device.

It enables pretty printing by default with width of 80 characters. The width can be changed by explicitly passing the :width option.

Examples

IO.inspect Process.list, width: 40

Inspects the item with options using the given device.

Returns the size of an iodata.

Inlined by the compiler.

Examples

iex> IO.iodata_length([1, 2|<<3, 4>>])
4

Converts iodata (a list of integers representing bytes, lists and binaries) into a binary.

Notice that this function treats lists of integers as raw bytes and does not perform any kind of encoding conversion. If you want to convert from a char list to a string (UTF-8 encoded), please use chardata_to_string/1 instead.

If this function receives a binary, the same binary is returned.

Inlined by the compiler.

Examples

iex> bin1 = <<1, 2, 3>>
iex> bin2 = <<4, 5>>
iex> bin3 = <<6>>
iex> IO.iodata_to_binary([bin1, 1, [2, 3, bin2], 4|bin3])
<<1,2,3,1,2,3,4,5,4,6>>

iex> bin = <<1, 2, 3>>
iex> IO.iodata_to_binary(bin)
<<1,2,3>>

Writes the argument to the device, similar to write/2, but adds a newline at the end. The argument is expected to be a chardata.

Reads count characters from the IO device, a whole :line or the whole device with :all.

It returns:

• data - the input characters

• :eof - end of file was encountered

• {:error, reason} - other (rare) error condition; for instance, {:error, :estale} if reading from an NFS volume

If :all is given, :eof is never returned, but an empty string in case the device has reached EOF.

Converts the io device into a IO.Stream.

An IO.Stream implements both Enumerable and Collectable, allowing it to be used for both read and write.

The device is iterated line by line if :line is given or by a given number of codepoints.

This reads the IO as utf-8. Check out IO.binstream/2 to handle the IO as a raw binary.

Note that an IO stream has side effects and every time you go over the stream you may get different results.

Examples

Here is an example on how we mimic an echo server from the command line:

Enum.each IO.stream(:stdio, :line), &IO.write(&1)

Writes the given argument to the given device.

By default the device is the standard output. It returns :ok if it succeeds.

Examples

IO.write "sample"
#=> "sample"

IO.write :stderr, "error"
#=> "error"