Output channels.
type t = out_channelThe type of output channel.
type open_flag = open_flag = | Open_rdonlyopen for reading.
*)| Open_wronlyopen for writing.
*)| Open_appendopen for appending: always write at end of file.
*)| Open_creatcreate the file if it does not exist.
*)| Open_truncempty the file if it already exists.
*)| Open_exclfail if Open_creat and the file already exists.
*)| Open_binaryopen in binary mode (no conversion).
*)| Open_textopen in text mode (may perform conversions).
*)| Open_nonblockopen in non-blocking mode.
*)Opening modes for open_gen.
val stdout : tThe standard output for the process.
val stderr : tThe standard error output for the process.
val open_bin : string -> tOpen the named file for writing, and return a new output channel on that file, positioned at the beginning of the file. The file is truncated to zero length if it already exists. It is created if it does not already exists.
val open_text : string -> tval with_open_bin : string -> (t -> 'a) -> 'awith_open_bin fn f opens a channel oc on file fn and returns f
oc. After f returns, either with a value or by raising an exception, oc is guaranteed to be closed.
val with_open_text : string -> (t -> 'a) -> 'aLike with_open_bin, but the channel is opened in text mode (see open_text).
Like with_open_bin, but can specify the opening mode and file permission, in case the file must be created (see open_gen).
val seek : t -> int64 -> unitseek chan pos sets the current writing position to pos for channel chan. This works only for regular files. On files of other kinds (such as terminals, pipes and sockets), the behavior is unspecified.
val pos : t -> int64Return the current writing position for the given channel. Does not work on channels opened with the Open_append flag (returns unspecified results).
For files opened in text mode under Windows, the returned position is approximate (owing to end-of-line conversion); in particular, saving the current position with pos, then going back to this position using seek will not work. For this programming idiom to work reliably and portably, the file must be opened in binary mode.
val length : t -> int64Return the size (number of characters) of the regular file on which the given channel is opened. If the channel is opened on a file that is not a regular file, the result is meaningless.
val close : t -> unitClose the given channel, flushing all buffered write operations. Output functions raise a Sys_error exception when they are applied to a closed output channel, except close and flush, which do nothing when applied to an already closed channel. Note that close may raise Sys_error if the operating system signals an error when flushing or closing.
val flush : t -> unitFlush the buffer associated with the given output channel, performing all pending writes on that channel. Interactive programs must be careful about flushing standard output and standard error at the right time.
val output_char : t -> char -> unitWrite the character on the given output channel.
val output_byte : t -> int -> unitWrite one 8-bit integer (as the single character with that code) on the given output channel. The given integer is taken modulo 256.
val output_string : t -> string -> unitWrite the string on the given output channel.
val output_bytes : t -> bytes -> unitWrite the byte sequence on the given output channel.
val output : t -> bytes -> int -> int -> unitoutput oc buf pos len writes len characters from byte sequence buf, starting at offset pos, to the given output channel oc.
val output_substring : t -> string -> int -> int -> unitSame as output but take a string as argument instead of a byte sequence.
val set_binary_mode : t -> bool -> unitset_binary_mode oc true sets the channel oc to binary mode: no translations take place during output.
set_binary_mode oc false sets the channel oc to text mode: depending on the operating system, some translations may take place during output. For instance, under Windows, end-of-lines will be translated from \n to \r\n.
This function has no effect under operating systems that do not distinguish between text mode and binary mode.
val set_buffered : t -> bool -> unitset_buffered oc true sets the channel oc to buffered mode. In this mode, data output on oc will be buffered until either the internal buffer is full or the function flush or flush_all is called, at which point it will be sent to the output device.
set_buffered oc false sets the channel oc to unbuffered mode. In this mode, data output on oc will be sent to the output device immediately.
All channels are open in buffered mode by default.
val is_buffered : t -> boolis_buffered oc returns whether the channel oc is buffered (see set_buffered).