ocaml/stdlib/printf.mli

239 lines
9.7 KiB
OCaml

(***********************************************************************)
(* *)
(* OCaml *)
(* *)
(* Xavier Leroy and Pierre Weis, projet Cristal, INRIA Rocquencourt *)
(* *)
(* Copyright 1996 Institut National de Recherche en Informatique et *)
(* en Automatique. All rights reserved. This file is distributed *)
(* under the terms of the GNU Library General Public License, with *)
(* the special exception on linking described in file ../LICENSE. *)
(* *)
(***********************************************************************)
(** Formatted output functions. *)
val fprintf : out_channel -> ('a, out_channel, unit) format -> 'a
(** [fprintf outchan format arg1 ... argN] formats the arguments
[arg1] to [argN] according to the format string [format], and
outputs the resulting string on the channel [outchan].
The format string is a character string which contains two types of
objects: plain characters, which are simply copied to the output
channel, and conversion specifications, each of which causes
conversion and printing of arguments.
Conversion specifications have the following form:
[% [flags] [width] [.precision] type]
In short, a conversion specification consists in the [%] character,
followed by optional modifiers and a type which is made of one or
two characters.
The types and their meanings are:
- [d], [i]: convert an integer argument to signed decimal.
- [u], [n], [l], [L], or [N]: convert an integer argument to
unsigned decimal. Warning: [n], [l], [L], and [N] are
used for [scanf], and should not be used for [printf].
- [x]: convert an integer argument to unsigned hexadecimal,
using lowercase letters.
- [X]: convert an integer argument to unsigned hexadecimal,
using uppercase letters.
- [o]: convert an integer argument to unsigned octal.
- [s]: insert a string argument.
- [S]: convert a string argument to OCaml syntax (double quotes, escapes).
- [c]: insert a character argument.
- [C]: convert a character argument to OCaml syntax
(single quotes, escapes).
- [f]: convert a floating-point argument to decimal notation,
in the style [dddd.ddd].
- [F]: convert a floating-point argument to OCaml syntax ([dddd.]
or [dddd.ddd] or [d.ddd e+-dd]).
- [e] or [E]: convert a floating-point argument to decimal notation,
in the style [d.ddd e+-dd] (mantissa and exponent).
- [g] or [G]: convert a floating-point argument to decimal notation,
in style [f] or [e], [E] (whichever is more compact).
- [B]: convert a boolean argument to the string [true] or [false]
- [b]: convert a boolean argument (deprecated; do not use in new
programs).
- [ld], [li], [lu], [lx], [lX], [lo]: convert an [int32] argument to
the format specified by the second letter (decimal, hexadecimal, etc).
- [nd], [ni], [nu], [nx], [nX], [no]: convert a [nativeint] argument to
the format specified by the second letter.
- [Ld], [Li], [Lu], [Lx], [LX], [Lo]: convert an [int64] argument to
the format specified by the second letter.
- [a]: user-defined printer. Take two arguments and apply the
first one to [outchan] (the current output channel) and to the
second argument. The first argument must therefore have type
[out_channel -> 'b -> unit] and the second ['b].
The output produced by the function is inserted in the output of
[fprintf] at the current point.
- [t]: same as [%a], but take only one argument (with type
[out_channel -> unit]) and apply it to [outchan].
- [\{ fmt %\}]: convert a format string argument to its type digest.
The argument must have the same type as the internal format string
[fmt].
- [( fmt %)]: format string substitution. Take a format string
argument and substitute it to the internal format string [fmt]
to print following arguments. The argument must have the same
type as the internal format string [fmt].
- [!]: take no argument and flush the output.
- [%]: take no argument and output one [%] character.
- [\@]: take no argument and output one [\@] character.
- [,]: take no argument and output nothing: a no-op delimiter for
conversion specifications.
The optional [flags] are:
- [-]: left-justify the output (default is right justification).
- [0]: for numerical conversions, pad with zeroes instead of spaces.
- [+]: for signed numerical conversions, prefix number with a [+]
sign if positive.
- space: for signed numerical conversions, prefix number with a
space if positive.
- [#]: request an alternate formatting style for numbers.
The optional [width] is an integer indicating the minimal
width of the result. For instance, [%6d] prints an integer,
prefixing it with spaces to fill at least 6 characters.
The optional [precision] is a dot [.] followed by an integer
indicating how many digits follow the decimal point in the [%f],
[%e], and [%E] conversions. For instance, [%.4f] prints a [float] with
4 fractional digits.
The integer in a [width] or [precision] can also be specified as
[*], in which case an extra integer argument is taken to specify
the corresponding [width] or [precision]. This integer argument
precedes immediately the argument to print.
For instance, [%.*f] prints a [float] with as many fractional
digits as the value of the argument given before the float. *)
val printf : ('a, out_channel, unit) format -> 'a
(** Same as {!Printf.fprintf}, but output on [stdout]. *)
val eprintf : ('a, out_channel, unit) format -> 'a
(** Same as {!Printf.fprintf}, but output on [stderr]. *)
val sprintf : ('a, unit, string) format -> 'a
(** Same as {!Printf.fprintf}, but instead of printing on an output channel,
return a string containing the result of formatting the arguments. *)
val bprintf : Buffer.t -> ('a, Buffer.t, unit) format -> 'a
(** Same as {!Printf.fprintf}, but instead of printing on an output channel,
append the formatted arguments to the given extensible buffer
(see module {!Buffer}). *)
val ifprintf : 'a -> ('b, 'a, unit) format -> 'b
(** Same as {!Printf.fprintf}, but does not print anything.
Useful to ignore some material when conditionally printing.
@since 3.10.0
*)
(** Formatted output functions with continuations. *)
val kfprintf : (out_channel -> 'a) -> out_channel ->
('b, out_channel, unit, 'a) format4 -> 'b;;
(** Same as [fprintf], but instead of returning immediately,
passes the out channel to its first argument at the end of printing.
@since 3.09.0
*)
val ikfprintf : (out_channel -> 'a) -> out_channel ->
('b, out_channel, unit, 'a) format4 -> 'b
;;
(** Same as [kfprintf] above, but does not print anything.
Useful to ignore some material when conditionally printing.
@since 4.0
*)
val ksprintf : (string -> 'a) -> ('b, unit, string, 'a) format4 -> 'b;;
(** Same as [sprintf] above, but instead of returning the string,
passes it to the first argument.
@since 3.09.0
*)
val kbprintf : (Buffer.t -> 'a) -> Buffer.t ->
('b, Buffer.t, unit, 'a) format4 -> 'b;;
(** Same as [bprintf], but instead of returning immediately,
passes the buffer to its first argument at the end of printing.
@since 3.10.0
*)
(** Deprecated *)
val kprintf : (string -> 'a) -> ('b, unit, string, 'a) format4 -> 'b;;
(** A deprecated synonym for [ksprintf]. *)
(**/**)
(* The following is for system use only. Do not call directly. *)
module CamlinternalPr : sig
module Sformat : sig
type index;;
val index_of_int : int -> index;;
external int_of_index : index -> int = "%identity";;
external unsafe_index_of_int : int -> index = "%identity";;
val succ_index : index -> index;;
val add_int_index : int -> index -> index;;
val sub : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> index -> int -> string;;
val to_string : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> string;;
external length : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> int
= "%string_length";;
external get : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> int -> char
= "%string_safe_get";;
external unsafe_to_string : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> string
= "%identity";;
external unsafe_get : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> int -> char
= "%string_unsafe_get";;
end;;
module Tformat : sig
type ac = {
mutable ac_rglr : int;
mutable ac_skip : int;
mutable ac_rdrs : int;
};;
val ac_of_format : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> ac;;
val count_printing_arguments_of_format :
('a, 'b, 'c, 'd, 'e, 'f) format6 -> int;;
val sub_format :
(('a, 'b, 'c, 'd, 'e, 'f) format6 -> int) ->
(('a, 'b, 'c, 'd, 'e, 'f) format6 -> int -> char -> int) ->
char ->
('a, 'b, 'c, 'd, 'e, 'f) format6 ->
int ->
int
val summarize_format_type : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> string
val scan_format : ('a, 'b, 'c, 'd, 'e, 'f) format6 ->
'g array ->
Sformat.index ->
int ->
(Sformat.index -> string -> int -> 'h) ->
(Sformat.index -> 'i -> 'j -> int -> 'h) ->
(Sformat.index -> 'k -> int -> 'h) ->
(Sformat.index -> int -> 'h) ->
(Sformat.index -> ('l, 'm, 'n, 'o, 'p, 'q) format6 -> int -> 'h) ->
'h
val kapr :
(('a, 'b, 'c, 'd, 'e, 'f) format6 -> Obj.t array -> 'g) ->
('a, 'b, 'c, 'd, 'e, 'f) format6 ->
'g
end;;
end;;