package nonstd
Library
Module
Module type
Parameter
Class
Class type
include module type of struct include Printf end
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. The flag#
adds underscores to large values for readability.u
,n
,l
,L
, orN
: convert an integer argument to unsigned decimal. Warning:n
,l
,L
, andN
are used forscanf
, and should not be used forprintf
. The flag#
adds underscores to large values for readability.x
: convert an integer argument to unsigned hexadecimal, using lowercase letters. The flag#
adds a0x
prefix to non zero values.X
: convert an integer argument to unsigned hexadecimal, using uppercase letters. The flag#
adds a0X
prefix to non zero values.o
: convert an integer argument to unsigned octal. The flag#
adds a0
prefix to non zero values.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 styledddd.ddd
.F
: convert a floating-point argument to OCaml syntax (dddd.
ordddd.ddd
ord.ddd e+-dd
). Converts to hexadecimal with the#
flag (seeh
).e
orE
: convert a floating-point argument to decimal notation, in the styled.ddd e+-dd
(mantissa and exponent).g
orG
: convert a floating-point argument to decimal notation, in stylef
ore
,E
(whichever is more compact). Moreover, any trailing zeros are removed from the fractional part of the result and the decimal-point character is removed if there is no fractional part remaining.h
orH
: convert a floating-point argument to hexadecimal notation, in the style0xh.hhhh p+-dd
(hexadecimal mantissa, exponent in decimal and denotes a power of 2).B
: convert a boolean argument to the stringtrue
orfalse
b
: convert a boolean argument (deprecated; do not use in new programs).ld
,li
,lu
,lx
,lX
,lo
: convert anint32
argument to the format specified by the second letter (decimal, hexadecimal, etc).nd
,ni
,nu
,nx
,nX
,no
: convert anativeint
argument to the format specified by the second letter.Ld
,Li
,Lu
,Lx
,LX
,Lo
: convert anint64
argument to the format specified by the second letter.a
: user-defined printer. Take two arguments and apply the first one tooutchan
(the current output channel) and to the second argument. The first argument must therefore have typeout_channel -> 'b -> unit
and the second'b
. The output produced by the function is inserted in the output offprintf
at the current point.t
: same as%a
, but take only one argument (with typeout_channel -> unit
) and apply it tooutchan
.\{ fmt %\}
: convert a format string argument to its type digest. The argument must have the same type as the internal format stringfmt
.( fmt %)
: format string substitution. Take a format string argument and substitute it to the internal format stringfmt
to print following arguments. The argument must have the same type as the internal format stringfmt
.!
: 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 the integer types and the floating-point typeF
.
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
, %E
, %h
, and %H
conversions or the maximum number of significant digits to appear for the %F
, %g
and %G
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.
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 : 'b -> ('a, 'b, 'c, unit) format4 -> 'a
Same as Printf.fprintf
, but does not print anything. Useful to ignore some material when conditionally printing.
Same as Printf.bprintf
, but does not print anything. Useful to ignore some material when conditionally printing.
Formatted output functions with continuations.
val kfprintf :
(out_channel -> 'd) ->
out_channel ->
('a, out_channel, unit, 'd) format4 ->
'a
Same as fprintf
, but instead of returning immediately, passes the out channel to its first argument at the end of printing.
val ikfprintf : ('b -> 'd) -> 'b -> ('a, 'b, 'c, 'd) format4 -> 'a
Same as kfprintf
above, but does not print anything. Useful to ignore some material when conditionally printing.
val ksprintf : (string -> 'd) -> ('a, unit, string, 'd) format4 -> 'a
Same as sprintf
above, but instead of returning the string, passes it to the first argument.
Same as bprintf
, but instead of returning immediately, passes the buffer to its first argument at the end of printing.
Same as kbprintf
above, but does not print anything. Useful to ignore some material when conditionally printing.
Deprecated
val kprintf : (string -> 'b) -> ('a, unit, string, 'b) format4 -> 'a
A deprecated synonym for ksprintf
.
module List : sig ... end
module Array = ArrayLabels
module Option : sig ... end
module Int : sig ... end
module Float : sig ... end