(***********************************************************************) (* *) (* Objective Caml *) (* *) (* Xavier Leroy, 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. *) (* *) (***********************************************************************) (* $Id$ *) (* Module [Printf]: 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. - [o]: convert an integer argument to unsigned octal. - [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]. - [%]: take no argument and output one [%] character. - Refer to the C library [printf] function for the meaning of flags and field width specifiers. Warning: if too few arguments are provided, for instance because the [printf] function is partially applied, the format is immediately printed up to the conversion of the first missing argument; printing will then resume when the missing arguments are provided. For example, [List.iter (printf "x=%d y=%d " 1) [2;3]] prints [x=1 y=2 3] instead of the expected [x=1 y=2 x=1 y=3]. To get the expected behavior, do [List.iter (fun y -> printf "x=%d y=%d " 1 y) [2;3]]. *) val printf: ('a, out_channel, unit) format -> 'a (* Same as [fprintf], but output on [stdout]. *) val eprintf: ('a, out_channel, unit) format -> 'a (* Same as [fprintf], but output on [stderr]. *) val sprintf: ('a, unit, string) format -> 'a (* Same as [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 [fprintf], but instead of printing on an output channel, append the formatted arguments to the given extensible buffer (see module [Buffer]). *)