- Exceptions
- Comparisons
- Boolean operations
- Debugging
- Composition operators
- Integer arithmetic
- Bitwise operations
- Floating-point arithmetic
- String operations
- Character operations
- Unit operations
- String conversion functions
- Pair operations
- List operations
- Input/output
- Output functions on standard output
- Output functions on standard error
- Input functions on standard input
- General output functions
- General input functions
- Operations on large files
- References
- Result type
- Operations on format strings
- Program termination
package ocaml-base-compiler
The initially opened module.
This module provides the basic operations over the built-in types (numbers, booleans, byte sequences, strings, exceptions, references, lists, arrays, input-output channels, ...).
This module is automatically opened at the beginning of each compilation. All components of this module can therefore be referred by their short name, without prefixing them by Pervasives
.
Exceptions
The Exit
exception is not raised by any library function. It is provided for use in your programs.
Comparisons
e1 = e2
tests for structural equality of e1
and e2
. Mutable structures (e.g. references and arrays) are equal if and only if their current contents are structurally equal, even if the two mutable objects are not the same physical object. Equality between functional values raises Invalid_argument
. Equality between cyclic data structures may not terminate.
Negation of Pervasives.(=)
.
See Pervasives.(>=)
.
See Pervasives.(>=)
.
See Pervasives.(>=)
.
Structural ordering functions. These functions coincide with the usual orderings over integers, characters, strings, byte sequences and floating-point numbers, and extend them to a total ordering over all types. The ordering is compatible with ( = )
. As in the case of ( = )
, mutable structures are compared by contents. Comparison between functional values raises Invalid_argument
. Comparison between cyclic structures may not terminate.
compare x y
returns 0
if x
is equal to y
, a negative integer if x
is less than y
, and a positive integer if x
is greater than y
. The ordering implemented by compare
is compatible with the comparison predicates =
, <
and >
defined above, with one difference on the treatment of the float value Pervasives.nan
. Namely, the comparison predicates treat nan
as different from any other float value, including itself; while compare
treats nan
as equal to itself and less than any other float value. This treatment of nan
ensures that compare
defines a total ordering relation.
compare
applied to functional values may raise Invalid_argument
. compare
applied to cyclic structures may not terminate.
The compare
function can be used as the comparison function required by the Set.Make
and Map.Make
functors, as well as the List.sort
and Array.sort
functions.
Return the smaller of the two arguments. The result is unspecified if one of the arguments contains the float value nan
.
Return the greater of the two arguments. The result is unspecified if one of the arguments contains the float value nan
.
e1 == e2
tests for physical equality of e1
and e2
. On mutable types such as references, arrays, byte sequences, records with mutable fields and objects with mutable instance variables, e1 == e2
is true if and only if physical modification of e1
also affects e2
. On non-mutable types, the behavior of ( == )
is implementation-dependent; however, it is guaranteed that e1 == e2
implies compare e1 e2 = 0
.
Negation of Pervasives.(==)
.
Boolean operations
The boolean 'and'. Evaluation is sequential, left-to-right: in e1 && e2
, e1
is evaluated first, and if it returns false
, e2
is not evaluated at all.
The boolean 'or'. Evaluation is sequential, left-to-right: in e1 || e2
, e1
is evaluated first, and if it returns true
, e2
is not evaluated at all.
Debugging
__LOC__
returns the location at which this expression appears in the file currently being parsed by the compiler, with the standard error format of OCaml: "File %S, line %d, characters %d-%d".
__LINE__
returns the line number at which this expression appears in the file currently being parsed by the compiler.
__POS__
returns a tuple (file,lnum,cnum,enum)
, corresponding to the location at which this expression appears in the file currently being parsed by the compiler. file
is the current filename, lnum
the line number, cnum
the character position in the line and enum
the last character position in the line.
__LOC_OF__ expr
returns a pair (loc, expr)
where loc
is the location of expr
in the file currently being parsed by the compiler, with the standard error format of OCaml: "File %S, line %d, characters %d-%d".
__LINE__ expr
returns a pair (line, expr)
, where line
is the line number at which the expression expr
appears in the file currently being parsed by the compiler.
__POS_OF__ expr
returns a pair (loc,expr)
, where loc
is a tuple (file,lnum,cnum,enum)
corresponding to the location at which the expression expr
appears in the file currently being parsed by the compiler. file
is the current filename, lnum
the line number, cnum
the character position in the line and enum
the last character position in the line.
Composition operators
Reverse-application operator: x |> f |> g
is exactly equivalent to g (f (x))
.
Application operator: g @@ f @@ x
is exactly equivalent to g (f (x))
.
Integer arithmetic
Integers are 31 bits wide (or 63 bits on 64-bit processors). All operations are taken modulo 231 (or 263). They do not fail on overflow.
Integer division. Raise Division_by_zero
if the second argument is 0. Integer division rounds the real quotient of its arguments towards zero. More precisely, if x >= 0
and y > 0
, x / y
is the greatest integer less than or equal to the real quotient of x
by y
. Moreover, (- x) / y = x / (- y) = - (x / y)
.
Integer remainder. If y
is not zero, the result of x mod y
satisfies the following properties: x = (x / y) * y + x mod y
and abs(x mod y) <= abs(y) - 1
. If y = 0
, x mod y
raises Division_by_zero
. Note that x mod y
is negative only if x < 0
. Raise Division_by_zero
if y
is zero.
Return the absolute value of the argument. Note that this may be negative if the argument is min_int
.
Bitwise operations
n lsl m
shifts n
to the left by m
bits. The result is unspecified if m < 0
or m >= bitsize
, where bitsize
is 32
on a 32-bit platform and 64
on a 64-bit platform.
n lsr m
shifts n
to the right by m
bits. This is a logical shift: zeroes are inserted regardless of the sign of n
. The result is unspecified if m < 0
or m >= bitsize
.
n asr m
shifts n
to the right by m
bits. This is an arithmetic shift: the sign bit of n
is replicated. The result is unspecified if m < 0
or m >= bitsize
.
Floating-point arithmetic
OCaml's floating-point numbers follow the IEEE 754 standard, using double precision (64 bits) numbers. Floating-point operations never raise an exception on overflow, underflow, division by zero, etc. Instead, special IEEE numbers are returned as appropriate, such as infinity
for 1.0 /. 0.0
, neg_infinity
for -1.0 /. 0.0
, and nan
('not a number') for 0.0 /. 0.0
. These special numbers then propagate through floating-point computations as expected: for instance, 1.0 /. infinity
is 0.0
, and any arithmetic operation with nan
as argument returns nan
as result.
expm1 x
computes exp x -. 1.0
, giving numerically-accurate results even if x
is close to 0.0
.
log1p x
computes log(1.0 +. x)
(natural logarithm), giving numerically-accurate results even if x
is close to 0.0
.
Arc cosine. The argument must fall within the range [-1.0, 1.0]
. Result is in radians and is between 0.0
and pi
.
Arc sine. The argument must fall within the range [-1.0, 1.0]
. Result is in radians and is between -pi/2
and pi/2
.
atan2 y x
returns the arc tangent of y /. x
. The signs of x
and y
are used to determine the quadrant of the result. Result is in radians and is between -pi
and pi
.
hypot x y
returns sqrt(x *. x + y *. y)
, that is, the length of the hypotenuse of a right-angled triangle with sides of length x
and y
, or, equivalently, the distance of the point (x,y)
to origin. If one of x
or y
is infinite, returns infinity
even if the other is nan
.
Round above to an integer value. ceil f
returns the least integer value greater than or equal to f
. The result is returned as a float.
Round below to an integer value. floor f
returns the greatest integer value less than or equal to f
. The result is returned as a float.
copysign x y
returns a float whose absolute value is that of x
and whose sign is that of y
. If x
is nan
, returns nan
. If y
is nan
, returns either x
or -. x
, but it is not specified which.
mod_float a b
returns the remainder of a
with respect to b
. The returned value is a -. n *. b
, where n
is the quotient a /. b
rounded towards zero to an integer.
frexp f
returns the pair of the significant and the exponent of f
. When f
is zero, the significant x
and the exponent n
of f
are equal to zero. When f
is non-zero, they are defined by f = x *. 2 ** n
and 0.5 <= x < 1.0
.
Same as Pervasives.float_of_int
.
Same as Pervasives.int_of_float
.
Truncate the given floating-point number to an integer. The result is unspecified if the argument is nan
or falls outside the range of representable integers.
A special floating-point value denoting the result of an undefined operation such as 0.0 /. 0.0
. Stands for 'not a number'. Any floating-point operation with nan
as argument returns nan
as result. As for floating-point comparisons, =
, <
, <=
, >
and >=
return false
and <>
returns true
if one or both of their arguments is nan
.
The difference between 1.0
and the smallest exactly representable floating-point number greater than 1.0
.
The five classes of floating-point numbers, as determined by the Pervasives.classify_float
function.
val classify_float : float -> fpclass
Return the class of the given floating-point number: normal, subnormal, zero, infinite, or not a number.
String operations
More string operations are provided in module String
.
Character operations
More character operations are provided in module Char
.
Return the character with the given ASCII code. Raise Invalid_argument "char_of_int"
if the argument is outside the range 0--255.
Unit operations
Discard the value of its argument and return ()
. For instance, ignore(f x)
discards the result of the side-effecting function f
. It is equivalent to f x; ()
, except that the latter may generate a compiler warning; writing ignore(f x)
instead avoids the warning.
String conversion functions
Return the string representation of a boolean. As the returned values may be shared, the user should not modify them directly.
Convert the given string to a boolean. Raise Invalid_argument "bool_of_string"
if the string is not "true"
or "false"
.
Convert the given string to a boolean. Return None
if the string is not "true"
or "false"
.
Convert the given string to an integer. The string is read in decimal (by default), in hexadecimal (if it begins with 0x
or 0X
), in octal (if it begins with 0o
or 0O
), or in binary (if it begins with 0b
or 0B
). The _
(underscore) character can appear anywhere in the string and is ignored. Raise Failure "int_of_string"
if the given string is not a valid representation of an integer, or if the integer represented exceeds the range of integers representable in type int
.
Same as int_of_string
, but returs None
instead of raising.
Convert the given string to a float. The string is read in decimal (by default) or in hexadecimal (marked by 0x
or 0X
). The format of decimal floating-point numbers is [-] dd.ddd (e|E) [+|-] dd
, where d
stands for a decimal digit. The format of hexadecimal floating-point numbers is [-] 0(x|X) hh.hhh (p|P) [+|-] dd
, where h
stands for an hexadecimal digit and d
for a decimal digit. In both cases, at least one of the integer and fractional parts must be given; the exponent part is optional. The _
(underscore) character can appear anywhere in the string and is ignored. Depending on the execution platforms, other representations of floating-point numbers can be accepted, but should not be relied upon. Raise Failure "float_of_string"
if the given string is not a valid representation of a float.
Same as float_of_string
, but returns None
instead of raising.
Pair operations
List operations
More list operations are provided in module List
.
List concatenation. Not tail-recursive (length of the first argument).
Input/output
Note: all input/output functions can raise Sys_error
when the system calls they invoke fail.
val stdin : in_channel
The standard input for the process.
val stdout : out_channel
The standard output for the process.
val stderr : out_channel
The standard error output for the process.
Output functions on standard output
Print a string, followed by a newline character, on standard output and flush standard output.
Print a newline character on standard output, and flush standard output. This can be used to simulate line buffering of standard output.
Output functions on standard error
Print a string, followed by a newline character on standard error and flush standard error.
Print a newline character on standard error, and flush standard error.
Input functions on standard input
Flush standard output, then read characters from standard input until a newline character is encountered. Return the string of all characters read, without the newline character at the end.
Flush standard output, then read one line from standard input and convert it to an integer. Raise Failure "int_of_string"
if the line read is not a valid representation of an integer.
Flush standard output, then read one line from standard input and convert it to a floating-point number. The result is unspecified if the line read is not a valid representation of a floating-point number.
Flush standard output, then read one line from standard input and convert it to a floating-point number. Returns None
if the line read is not a valid representation of a floating-point number.
General output functions
type open_flag =
| Open_rdonly
(*open for reading.
*)| Open_wronly
(*open for writing.
*)| Open_append
(*open for appending: always write at end of file.
*)| Open_creat
(*create the file if it does not exist.
*)| Open_trunc
(*empty the file if it already exists.
*)| Open_excl
(*fail if Open_creat and the file already exists.
*)| Open_binary
(*open in binary mode (no conversion).
*)| Open_text
(*open in text mode (may perform conversions).
*)| Open_nonblock
(*open in non-blocking mode.
*)
Opening modes for Pervasives.open_out_gen
and Pervasives.open_in_gen
.
val open_out : string -> out_channel
Open the named file for writing, and return a new output channel on that file, positioned at the beginning of the file. The file is truncated to zero length if it already exists. It is created if it does not already exists.
val open_out_bin : string -> out_channel
Same as Pervasives.open_out
, but the file is opened in binary mode, so that no translation takes place during writes. On operating systems that do not distinguish between text mode and binary mode, this function behaves like Pervasives.open_out
.
val open_out_gen : open_flag list -> int -> string -> out_channel
open_out_gen mode perm filename
opens the named file for writing, as described above. The extra argument mode
specifies the opening mode. The extra argument perm
specifies the file permissions, in case the file must be created. Pervasives.open_out
and Pervasives.open_out_bin
are special cases of this function.
val flush : out_channel -> unit
Flush the buffer associated with the given output channel, performing all pending writes on that channel. Interactive programs must be careful about flushing standard output and standard error at the right time.
val output_char : out_channel -> char -> unit
Write the character on the given output channel.
val output_string : out_channel -> string -> unit
Write the string on the given output channel.
val output_bytes : out_channel -> bytes -> unit
Write the byte sequence on the given output channel.
val output : out_channel -> bytes -> int -> int -> unit
output oc buf pos len
writes len
characters from byte sequence buf
, starting at offset pos
, to the given output channel oc
. Raise Invalid_argument "output"
if pos
and len
do not designate a valid range of buf
.
val output_substring : out_channel -> string -> int -> int -> unit
Same as output
but take a string as argument instead of a byte sequence.
val output_byte : out_channel -> int -> unit
Write one 8-bit integer (as the single character with that code) on the given output channel. The given integer is taken modulo 256.
val output_binary_int : out_channel -> int -> unit
Write one integer in binary format (4 bytes, big-endian) on the given output channel. The given integer is taken modulo 232. The only reliable way to read it back is through the Pervasives.input_binary_int
function. The format is compatible across all machines for a given version of OCaml.
val output_value : out_channel -> 'a -> unit
Write the representation of a structured value of any type to a channel. Circularities and sharing inside the value are detected and preserved. The object can be read back, by the function Pervasives.input_value
. See the description of module Marshal
for more information. Pervasives.output_value
is equivalent to Marshal.to_channel
with an empty list of flags.
val seek_out : out_channel -> int -> unit
seek_out chan pos
sets the current writing position to pos
for channel chan
. This works only for regular files. On files of other kinds (such as terminals, pipes and sockets), the behavior is unspecified.
val pos_out : out_channel -> int
Return the current writing position for the given channel. Does not work on channels opened with the Open_append
flag (returns unspecified results).
val out_channel_length : out_channel -> int
Return the size (number of characters) of the regular file on which the given channel is opened. If the channel is opened on a file that is not a regular file, the result is meaningless.
val close_out : out_channel -> unit
Close the given channel, flushing all buffered write operations. Output functions raise a Sys_error
exception when they are applied to a closed output channel, except close_out
and flush
, which do nothing when applied to an already closed channel. Note that close_out
may raise Sys_error
if the operating system signals an error when flushing or closing.
val close_out_noerr : out_channel -> unit
Same as close_out
, but ignore all errors.
val set_binary_mode_out : out_channel -> bool -> unit
set_binary_mode_out oc true
sets the channel oc
to binary mode: no translations take place during output. set_binary_mode_out oc false
sets the channel oc
to text mode: depending on the operating system, some translations may take place during output. For instance, under Windows, end-of-lines will be translated from \n
to \r\n
. This function has no effect under operating systems that do not distinguish between text mode and binary mode.
General input functions
val open_in : string -> in_channel
Open the named file for reading, and return a new input channel on that file, positioned at the beginning of the file.
val open_in_bin : string -> in_channel
Same as Pervasives.open_in
, but the file is opened in binary mode, so that no translation takes place during reads. On operating systems that do not distinguish between text mode and binary mode, this function behaves like Pervasives.open_in
.
val open_in_gen : open_flag list -> int -> string -> in_channel
open_in_gen mode perm filename
opens the named file for reading, as described above. The extra arguments mode
and perm
specify the opening mode and file permissions. Pervasives.open_in
and Pervasives.open_in_bin
are special cases of this function.
val input_char : in_channel -> char
Read one character from the given input channel. Raise End_of_file
if there are no more characters to read.
val input_line : in_channel -> string
Read characters from the given input channel, until a newline character is encountered. Return the string of all characters read, without the newline character at the end. Raise End_of_file
if the end of the file is reached at the beginning of line.
val input : in_channel -> bytes -> int -> int -> int
input ic buf pos len
reads up to len
characters from the given channel ic
, storing them in byte sequence buf
, starting at character number pos
. It returns the actual number of characters read, between 0 and len
(inclusive). A return value of 0 means that the end of file was reached. A return value between 0 and len
exclusive means that not all requested len
characters were read, either because no more characters were available at that time, or because the implementation found it convenient to do a partial read; input
must be called again to read the remaining characters, if desired. (See also Pervasives.really_input
for reading exactly len
characters.) Exception Invalid_argument "input"
is raised if pos
and len
do not designate a valid range of buf
.
val really_input : in_channel -> bytes -> int -> int -> unit
really_input ic buf pos len
reads len
characters from channel ic
, storing them in byte sequence buf
, starting at character number pos
. Raise End_of_file
if the end of file is reached before len
characters have been read. Raise Invalid_argument "really_input"
if pos
and len
do not designate a valid range of buf
.
val really_input_string : in_channel -> int -> string
really_input_string ic len
reads len
characters from channel ic
and returns them in a new string. Raise End_of_file
if the end of file is reached before len
characters have been read.
val input_byte : in_channel -> int
Same as Pervasives.input_char
, but return the 8-bit integer representing the character. Raise End_of_file
if an end of file was reached.
val input_binary_int : in_channel -> int
Read an integer encoded in binary format (4 bytes, big-endian) from the given input channel. See Pervasives.output_binary_int
. Raise End_of_file
if an end of file was reached while reading the integer.
val input_value : in_channel -> 'a
Read the representation of a structured value, as produced by Pervasives.output_value
, and return the corresponding value. This function is identical to Marshal.from_channel
; see the description of module Marshal
for more information, in particular concerning the lack of type safety.
val seek_in : in_channel -> int -> unit
seek_in chan pos
sets the current reading position to pos
for channel chan
. This works only for regular files. On files of other kinds, the behavior is unspecified.
val pos_in : in_channel -> int
Return the current reading position for the given channel.
val in_channel_length : in_channel -> int
Return the size (number of characters) of the regular file on which the given channel is opened. If the channel is opened on a file that is not a regular file, the result is meaningless. The returned size does not take into account the end-of-line translations that can be performed when reading from a channel opened in text mode.
val close_in : in_channel -> unit
Close the given channel. Input functions raise a Sys_error
exception when they are applied to a closed input channel, except close_in
, which does nothing when applied to an already closed channel.
val close_in_noerr : in_channel -> unit
Same as close_in
, but ignore all errors.
val set_binary_mode_in : in_channel -> bool -> unit
set_binary_mode_in ic true
sets the channel ic
to binary mode: no translations take place during input. set_binary_mode_out ic false
sets the channel ic
to text mode: depending on the operating system, some translations may take place during input. For instance, under Windows, end-of-lines will be translated from \r\n
to \n
. This function has no effect under operating systems that do not distinguish between text mode and binary mode.
Operations on large files
module LargeFile : sig ... end
Operations on large files. This sub-module provides 64-bit variants of the channel functions that manipulate file positions and file sizes. By representing positions and sizes by 64-bit integers (type int64
) instead of regular integers (type int
), these alternate functions allow operating on files whose sizes are greater than max_int
.
References
The type of references (mutable indirection cells) containing a value of type 'a
.
val ref : 'a -> 'a ref
Return a fresh reference containing the given value.
val (!) : 'a ref -> 'a
!r
returns the current contents of reference r
. Equivalent to fun r -> r.contents
.
val (:=) : 'a ref -> 'a -> unit
r := a
stores the value of a
in reference r
. Equivalent to fun r v -> r.contents <- v
.
val incr : int ref -> unit
Increment the integer contained in the given reference. Equivalent to fun r -> r := succ !r
.
val decr : int ref -> unit
Decrement the integer contained in the given reference. Equivalent to fun r -> r := pred !r
.
Result type
Operations on format strings
Format strings are character strings with special lexical conventions that defines the functionality of formatted input/output functions. Format strings are used to read data with formatted input functions from module Scanf
and to print data with formatted output functions from modules Printf
and Format
.
Format strings are made of three kinds of entities:
- conversions specifications, introduced by the special character
'%'
followed by one or more characters specifying what kind of argument to read or print, - formatting indications, introduced by the special character
'@'
followed by one or more characters specifying how to read or print the argument, - plain characters that are regular characters with usual lexical conventions. Plain characters specify string literals to be read in the input or printed in the output.
There is an additional lexical rule to escape the special characters '%'
and '@'
in format strings: if a special character follows a '%'
character, it is treated as a plain character. In other words, "%%"
is considered as a plain '%'
and "%@"
as a plain '@'
.
For more information about conversion specifications and formatting indications available, read the documentation of modules Scanf
, Printf
and Format
.
Format strings have a general and highly polymorphic type ('a, 'b, 'c, 'd, 'e, 'f) format6
. The two simplified types, format
and format4
below are included for backward compatibility with earlier releases of OCaml.
The meaning of format string type parameters is as follows:
'a
is the type of the parameters of the format for formatted output functions (printf
-style functions);'a
is the type of the values read by the format for formatted input functions (scanf
-style functions).
'b
is the type of input source for formatted input functions and the type of output target for formatted output functions. Forprintf
-style functions from modulePrintf
,'b
is typicallyout_channel
; forprintf
-style functions from moduleFormat
,'b
is typicallyFormat.formatter
; forscanf
-style functions from moduleScanf
,'b
is typicallyScanf.Scanning.in_channel
.
Type argument 'b
is also the type of the first argument given to user's defined printing functions for %a
and %t
conversions, and user's defined reading functions for %r
conversion.
'c
is the type of the result of the%a
and%t
printing functions, and also the type of the argument transmitted to the first argument ofkprintf
-style functions or to thekscanf
-style functions.
'd
is the type of parameters for thescanf
-style functions.
'e
is the type of the receiver function for thescanf
-style functions.
'f
is the final result type of a formatted input/output function invocation: for theprintf
-style functions, it is typicallyunit
; for thescanf
-style functions, it is typically the result type of the receiver function.
type ('a, 'b, 'c, 'd, 'e, 'f) format6 =
('a, 'b, 'c, 'd, 'e, 'f) CamlinternalFormatBasics.format6
type ('a, 'b, 'c, 'd) format4 = ('a, 'b, 'c, 'c, 'c, 'd) format6
type ('a, 'b, 'c) format = ('a, 'b, 'c, 'c) format4
val string_of_format : ('a, 'b, 'c, 'd, 'e, 'f) format6 -> string
Converts a format string into a string.
format_of_string s
returns a format string read from the string literal s
. Note: format_of_string
can not convert a string argument that is not a literal. If you need this functionality, use the more general Scanf.format_from_string
function.
val (^^) :
('a, 'b, 'c, 'd, 'e, 'f) format6 ->
('f, 'b, 'c, 'e, 'g, 'h) format6 ->
('a, 'b, 'c, 'd, 'g, 'h) format6
f1 ^^ f2
catenates format strings f1
and f2
. The result is a format string that behaves as the concatenation of format strings f1
and f2
: in case of formatted output, it accepts arguments from f1
, then arguments from f2
; in case of formatted input, it returns results from f1
, then results from f2
.
Program termination
Terminate the process, returning the given status code to the operating system: usually 0 to indicate no errors, and a small positive integer to indicate failure. All open output channels are flushed with flush_all
. An implicit exit 0
is performed each time a program terminates normally. An implicit exit 2
is performed if the program terminates early because of an uncaught exception.
Register the given function to be called at program termination time. The functions registered with at_exit
will be called when the program executes Pervasives.exit
, or terminates, either normally or because of an uncaught exception. The functions are called in 'last in, first out' order: the function most recently added with at_exit
is called first.
- Exceptions
- Comparisons
- Boolean operations
- Debugging
- Composition operators
- Integer arithmetic
- Bitwise operations
- Floating-point arithmetic
- String operations
- Character operations
- Unit operations
- String conversion functions
- Pair operations
- List operations
- Input/output
- Output functions on standard output
- Output functions on standard error
- Input functions on standard input
- General output functions
- General input functions
- Operations on large files
- References
- Result type
- Operations on format strings
- Program termination