ocaml/stdlib/printf.mli

182 lines
8.3 KiB
OCaml

(***********************************************************************)
(* *)
(* Objective Caml *)
(* *)
(* 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. *)
(* *)
(***********************************************************************)
(* $Id$ *)
(** 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 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:
[% \[positional specifier\] \[flags\] \[width\] \[.precision\] 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], [n], [l], [L], or [N]: convert an integer argument to
signed decimal.
- [u]: convert an integer argument to unsigned decimal.
- [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]: insert a string argument in Caml syntax (double quotes, escapes).
- [c]: insert a character argument.
- [C]: insert a character argument in Caml 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 Caml 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 (for backward compatibility; 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. Takes 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 takes only one argument (with type
[out_channel -> unit]) and apply it to [outchan].
- [\{ fmt %\}]: convert a format string argument. The argument must
have the same type as the internal format string [fmt].
- [( fmt %)]: format string substitution. Takes a format string
argument and substitutes it to the internal format string [fmt]
to print following arguments. The argument must have the same
type as [fmt].
- [!]: take no argument and flush the output.
- [%]: take no argument and output one [%] character.
The optional [positional specifier] consists of an integer followed
by a [$]; the integer indicates which argument to use, the first
argument being denoted by 1.
The optional [flags] are:
- [-]: left-justify the output (default is right justification).
- [0]: for numerical conversions, pad with zeroes instead of spaces.
- [+]: for numerical conversions, prefix number with a [+] sign if positive.
- space: for numerical conversions, prefix number with a space if positive.
- [#]: request an alternate formatting style for numbers.
The optional [width] is an integer indicating the minimal
width of the result. For instance, [%6d] prints an integer,
prefixing it with spaces to fill at least 6 characters.
The optional [precision] is a dot [.] followed by an integer
indicating how many digits follow the decimal point in the [%f],
[%e], and [%E] conversions. For instance, [%.4f] prints a [float] with
4 fractional digits.
The integer in a [width] or [precision] can also be specified as
[*], in which case an extra integer argument is taken to specify
the corresponding [width] or [precision]. This integer argument
precedes immediately the argument to print, unless an optional
[positional specifier] is given to indicates which argument to
use. For instance, [%.*3$f] prints a [float] with as many fractional
digits as the value of the third argument. *)
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}). *)
(** 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. *)
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. *)
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. *)
val kprintf : (string -> 'a) -> ('b, unit, string, 'a) format4 -> 'b;;
(** A deprecated synonym for [ksprintf]. *)
(**/**)
(* For system use only. Don't call directly. *)
type index;;
external index_of_int : int -> index = "%identity";;
module Sformat : sig
external unsafe_to_string : ('a, 'b, 'c, 'd) format4 -> string
= "%identity"
external length : ('a, 'b, 'c, 'd) format4 -> int
= "%string_length"
external get : ('a, 'b, 'c, 'd) format4 -> int -> char
= "%string_safe_get"
external unsafe_get : ('a, 'b, 'c, 'd) format4 -> int -> char
= "%string_unsafe_get"
val sub : ('a, 'b, 'c, 'd) format4 -> int -> int -> string
val to_string : ('a, 'b, 'c, 'd) format4 -> string
end
val scan_format : ('a, 'b, 'c, 'd) format4 ->
'e array ->
index ->
int ->
(index -> string -> int -> 'f) ->
(index -> 'g -> 'h -> int -> 'f) ->
(index -> 'i -> int -> 'f) ->
(index -> int -> 'f) ->
(index -> ('j, 'k, 'l, 'm) format4 -> int -> 'f) -> 'f
val sub_format :
(('a, 'b, 'c, 'd) format4 -> int) ->
(('a, 'b, 'c, 'd) format4 -> int -> char -> int) ->
char -> ('a, 'b, 'c, 'd) format4 -> int -> int
val summarize_format_type : ('a, 'b, 'c, 'd) format4 -> string
val kapr :
(('a, 'b, 'c, 'd) format4 -> Obj.t array -> 'e) ->
('a, 'b, 'c, 'd) format4 -> 'e