1Printf(3)                        OCaml library                       Printf(3)
2
3
4

NAME

6       Printf - Formatted output functions.
7

Module

9       Module   Printf
10

Documentation

12       Module Printf
13        : sig end
14
15
16       Formatted output functions.
17
18
19
20
21
22
23
24       val  fprintf  :  Pervasives.out_channel -> ('a, Pervasives.out_channel,
25       unit) Pervasives.format -> 'a
26
27
28       fprintf outchan format arg1 ... argN formats the arguments arg1 to argN
29       according  to  the  format  string  format  , and outputs the resulting
30       string on the channel outchan .
31
32       The format is a character string which contains two types  of  objects:
33       plain  characters,  which  are simply copied to the output channel, and
34       conversion specifications, each of which causes conversion and printing
35       of arguments.
36
37       Conversion specifications have the following form:
38
39
40       % [positional specifier] [flags] [width] [.precision] type
41
42       In  short, a conversion specification consists in the % character, fol‐
43       lowed by optional modifiers and a type which is  made  of  one  or  two
44       characters. The types and their meanings are:
45
46
47       - d , i , n , l , L , or N : convert an integer argument to signed dec‐
48       imal.
49
50       - u : convert an integer argument to unsigned decimal.
51
52       - x : convert an integer argument to unsigned hexadecimal, using lower‐
53       case letters.
54
55       - X : convert an integer argument to unsigned hexadecimal, using upper‐
56       case letters.
57
58       - o : convert an integer argument to unsigned octal.
59
60       - s : insert a string argument.
61
62       - S : insert a string argument in Caml syntax (double quotes, escapes).
63
64       - c : insert a character argument.
65
66       - C : insert a  character  argument  in  Caml  syntax  (single  quotes,
67       escapes).
68
69       -  f  :  convert  a floating-point argument to decimal notation, in the
70       style dddd.ddd .
71
72       - F : convert a floating-point argument to  Caml  syntax  (  dddd.   or
73       dddd.ddd or d.ddd e+-dd ).
74
75       -  e  or  E : convert a floating-point argument to decimal notation, in
76       the style d.ddd e+-dd (mantissa and exponent).
77
78       - g or G : convert a floating-point argument to  decimal  notation,  in
79       style f or e , E (whichever is more compact).
80
81       - B : convert a boolean argument to the string true or false
82
83
84       -  b  :  convert a boolean argument (for backward compatibility; do not
85       use in new programs).
86
87       - ld , li , lu , lx , lX , lo : convert an int32 argument to the format
88       specified by the second letter (decimal, hexadecimal, etc).
89
90       -  nd  ,  ni  , nu , nx , nX , no : convert a nativeint argument to the
91       format specified by the second letter.
92
93       - Ld , Li , Lu , Lx , LX , Lo : convert an int64 argument to the format
94       specified by the second letter.
95
96       - a : user-defined printer. Takes two arguments and apply the first one
97       to outchan (the current output channel) and to the second argument. The
98       first  argument  must therefore have type out_channel -> 'b -> unit and
99       the second 'b .  The output produced by the function is inserted in the
100       output of fprintf at the current point.
101
102       -  t  : same as %a , but takes only one argument (with type out_channel
103       -> unit ) and apply it to outchan .
104
105       - { fmt %} : convert a format string argument. The argument  must  have
106       the same type as the internal format string fmt .
107
108       - ( fmt %) : format string substitution. Takes a format string argument
109       and substitutes it to the internal format string fmt to print following
110       arguments. The argument must have the same type as fmt .
111
112       - !  : take no argument and flush the output.
113
114       - % : take no argument and output one % character.
115
116       The  optional positional specifier consists of an integer followed by a
117       $ ; the integer indicates which argument to  use,  the  first  argument
118       being denoted by 1.
119
120       The optional flags are:
121
122       - - : left-justify the output (default is right justification).
123
124       - 0 : for numerical conversions, pad with zeroes instead of spaces.
125
126       -  +  : for numerical conversions, prefix number with a + sign if posi‐
127       tive.
128
129       -space: for numerical conversions, prefix number with a space if  posi‐
130       tive.
131
132       - # : request an alternate formatting style for numbers.
133
134       The  optional  width  is an integer indicating the minimal width of the
135       result. For instance, %6d prints an integer, prefixing it  with  spaces
136       to fill at least 6 characters.
137
138       The  optional  precision  is a dot .  followed by an integer indicating
139       how many digits follow the decimal point in the %f , %e , and  %E  con‐
140       versions. For instance, %.4f prints a float with 4 fractional digits.
141
142       The  integer  in  a  width or precision can also be specified as * , in
143       which case an extra integer argument is taken  to  specify  the  corre‐
144       sponding  width  or  precision . This integer argument precedes immedi‐
145       ately the argument to print, unless an optional positional specifier is
146       given to indicates which argument to use. For instance, %.*3$f prints a
147       float with as many fractional digits as the value of  the  third  argu‐
148       ment.
149
150
151
152
153       val printf : ('a, Pervasives.out_channel, unit) Pervasives.format -> 'a
154
155       Same as Printf.fprintf , but output on stdout .
156
157
158
159
160       val  eprintf  : ('a, Pervasives.out_channel, unit) Pervasives.format ->
161       'a
162
163       Same as Printf.fprintf , but output on stderr .
164
165
166
167
168       val sprintf : ('a, unit, string) Pervasives.format -> 'a
169
170       Same as Printf.fprintf , but instead of printing on an output  channel,
171       return a string containing the result of formatting the arguments.
172
173
174
175
176       val bprintf : Buffer.t -> ('a, Buffer.t, unit) Pervasives.format -> 'a
177
178       Same  as Printf.fprintf , but instead of printing on an output channel,
179       append the formatted arguments to the given extensible buffer (see mod‐
180       ule Buffer ).
181
182
183
184
185       val kfprintf : (Pervasives.out_channel -> 'a) -> Pervasives.out_channel
186       -> ('b, Pervasives.out_channel, unit, 'a) format4 -> 'b
187
188       Same as fprintf , but instead of returning immediately, passes the  out
189       channel to its first argument at the end of printing.
190
191
192
193
194       val ksprintf : (string -> 'a) -> ('b, unit, string, 'a) format4 -> 'b
195
196       Same  as  sprintf above, but instead of returning the string, passes it
197       to the first argument.
198
199
200
201
202       val kprintf : (string -> 'a) -> ('b, unit, string, 'a) format4 -> 'b
203
204       A deprecated synonym for ksprintf .
205
206
207
208
209
210
211OCamldoc                          2007-05-24                         Printf(3)