Provided by: ocaml-man_4.13.1-4ubuntu1_all 
NAME
Printf - Formatted output functions.
Module
Module Printf
Documentation
Module Printf
: sig end
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. The flag # adds underscores to
large values for readability.
- 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 . The flag # adds
underscores to large values for readability.
- x : convert an integer argument to unsigned hexadecimal, using lowercase letters. The
flag # adds a 0x prefix to non zero values.
- X : convert an integer argument to unsigned hexadecimal, using uppercase letters. The
flag # adds a 0X prefix to non zero values.
- o : convert an integer argument to unsigned octal. The flag # adds a 0 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 style dddd.ddd .
- F : convert a floating-point argument to OCaml syntax ( dddd. or dddd.ddd or d.ddd
e+-dd ). Converts to hexadecimal with the # flag (see h ).
- 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). 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 or H : convert a floating-point argument to hexadecimal notation, in the style
0xh.hhhh p+-dd (hexadecimal mantissa, exponent in decimal and denotes a power of 2).
- 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 the integer types and the floating-point
type F .
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.
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 : 'b -> ('a, 'b, 'c, unit) format4 -> 'a
Same as Printf.fprintf , but does not print anything. Useful to ignore some material when
conditionally printing.
Since 3.10.0
val ibprintf : Buffer.t -> ('a, Buffer.t, unit) format -> 'a
Same as Printf.bprintf , but does not print anything. Useful to ignore some material when
conditionally printing.
Since 4.11.0
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.
Since 3.09.0
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.
Since 4.01.0
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.
Since 3.09.0
val kbprintf : (Buffer.t -> 'd) -> Buffer.t -> ('a, Buffer.t, unit, 'd) format4 -> 'a
Same as bprintf , but instead of returning immediately, passes the buffer to its first
argument at the end of printing.
Since 3.10.0
val ikbprintf : (Buffer.t -> 'd) -> Buffer.t -> ('a, Buffer.t, unit, 'd) format4 -> 'a
Same as kbprintf above, but does not print anything. Useful to ignore some material when
conditionally printing.
Since 4.11.0
Deprecated
val kprintf : (string -> 'b) -> ('a, unit, string, 'b) format4 -> 'a
A deprecated synonym for ksprintf .