ocaml/stdlib/printf.mli

49 lines
2.7 KiB
OCaml
Raw Normal View History

(* Formatting printing 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 one argument.
Conversion specifications consist in the [%] character, followed
by optional flags and field widths, followed by one conversion
character. The conversion characters and their meanings are:
- [d] or [i]: 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.
- [s]: insert a string argument
- [c]: insert a character argument
- [f]: convert a floating-point argument to decimal notation,
in the style [dddd.ddd]
- [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]
- [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 therefore 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].
- Refer to the C library [printf] function for the meaning of
flags and field width specifiers. *)
val printf: ('a, out_channel, unit) format -> 'a
(* Same as [fprintf], but output on [std_out]. *)
val eprintf: ('a, out_channel, unit) format -> 'a
(* Same as [fprintf], but output on [std_err]. *)
val sprintf: ('a, unit, string) format -> 'a
(* Same as [printf], but return the result of formatting in a
string. *)