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Module Printf: formatting printing functions |
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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).