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/Elixir 1.4

Integer

Functions for working with integers.

Summary

Functions

digits(integer, base \\ 10): Returns the ordered digits for the given integer
floor_div(dividend, divisor): Performs a floored integer division
mod(dividend, divisor): Computes the modulo remainder of an integer division
parse(binary, base \\ 10): Parses a text representation of an integer
to_charlist(integer): Returns a charlist which corresponds to the text representation of the given integer
to_charlist(integer, base): Returns a charlist which corresponds to the text representation of integer in the given base
to_string(integer): Returns a binary which corresponds to the text representation of integer
to_string(integer, base): Returns a binary which corresponds to the text representation of integer in the given base
undigits(digits, base \\ 10): Returns the integer represented by the ordered digits

Macros

is_even(integer): Determines if an integer is even
is_odd(integer): Determines if integer is odd

Functions

digits(integer, base \\ 10)

digits(integer, pos_integer) :: [integer, ...]

Returns the ordered digits for the given integer.

An optional base value may be provided representing the radix for the returned digits. This one must be an integer >= 2.

Examples

iex> Integer.digits(123)
[1, 2, 3]

iex> Integer.digits(170, 2)
[1, 0, 1, 0, 1, 0, 1, 0]

iex> Integer.digits(-170, 2)
[-1, 0, -1, 0, -1, 0, -1, 0]

floor_div(dividend, divisor)

floor_div(integer, neg_integer | pos_integer) :: integer

Performs a floored integer division.

Raises an ArithmeticError exception if one of the arguments is not an integer, or when the divisor is 0.

Integer.floor_div/2 performs floored integer division. This means that the result is always rounded towards negative infinity.

If you want to perform truncated integer division (rounding towards zero), use Kernel.div/2 instead.

Examples

iex> Integer.floor_div(5, 2)
2
iex> Integer.floor_div(6, -4)
-2
iex> Integer.floor_div(-99, 2)
-50

mod(dividend, divisor)

mod(integer, neg_integer | pos_integer) :: integer

Computes the modulo remainder of an integer division.

Integer.mod/2 uses floored division, which means that the result will always have the sign of the divisor.

Raises an ArithmeticError exception if one of the arguments is not an integer, or when the divisor is 0.

Examples

iex> Integer.mod(5, 2)
1
iex> Integer.mod(6, -4)
-2

parse(binary, base \\ 10)

parse(binary, 2..36) :: {integer, binary} | :error | no_return

Parses a text representation of an integer.

An optional base to the corresponding integer can be provided. If base is not given, 10 will be used.

If successful, returns a tuple in the form of {integer, remainder_of_binary}. Otherwise :error.

Raises an error if base is less than 2 or more than 36.

If you want to convert a string-formatted integer directly to a integer, String.to_integer/1 or String.to_integer/2 can be used instead.

Examples

iex> Integer.parse("34")
{34, ""}

iex> Integer.parse("34.5")
{34, ".5"}

iex> Integer.parse("three")
:error

iex> Integer.parse("34", 10)
{34, ""}

iex> Integer.parse("f4", 16)
{244, ""}

iex> Integer.parse("Awww++", 36)
{509216, "++"}

iex> Integer.parse("fab", 10)
:error

iex> Integer.parse("a2", 38)
** (ArgumentError) invalid base 38

to_charlist(integer)

to_charlist(integer) :: charlist

Returns a charlist which corresponds to the text representation of the given integer.

Inlined by the compiler.

Examples

iex> Integer.to_charlist(123)
'123'

iex> Integer.to_charlist(+456)
'456'

iex> Integer.to_charlist(-789)
'-789'

iex> Integer.to_charlist(0123)
'123'

to_charlist(integer, base)

to_charlist(integer, 2..36) :: charlist

Returns a charlist which corresponds to the text representation of integer in the given base.

base can be an integer between 2 and 36.

Inlined by the compiler.

Examples

iex> Integer.to_charlist(100, 16)
'64'

iex> Integer.to_charlist(-100, 16)
'-64'

iex> Integer.to_charlist(882681651, 36)
'ELIXIR'

to_string(integer)

to_string(integer) :: String.t

Returns a binary which corresponds to the text representation of integer.

Inlined by the compiler.

Examples

iex> Integer.to_string(123)
"123"

iex> Integer.to_string(+456)
"456"

iex> Integer.to_string(-789)
"-789"

iex> Integer.to_string(0123)
"123"

to_string(integer, base)

to_string(integer, 2..36) :: String.t

Returns a binary which corresponds to the text representation of integer in the given base.

base can be an integer between 2 and 36.

Inlined by the compiler.

Examples

iex> Integer.to_string(100, 16)
"64"

iex> Integer.to_string(-100, 16)
"-64"

iex> Integer.to_string(882681651, 36)
"ELIXIR"

undigits(digits, base \\ 10)

undigits([integer], integer) :: integer

Returns the integer represented by the ordered digits.

An optional base value may be provided representing the radix for the digits. This one can be an integer >= 2.

Examples

iex> Integer.undigits([1, 2, 3])
123

iex> Integer.undigits([1, 4], 16)
20

iex> Integer.undigits([])
0

Macros

is_even(integer)

Determines if an integer is even.

Returns true if the given integer is an even number, otherwise it returns false.

Allowed in guard clauses.

Examples

iex> Integer.is_even(10)
true

iex> Integer.is_even(5)
false

iex> Integer.is_even(-10)
true

iex> Integer.is_even(0)
true

is_odd(integer)

Determines if integer is odd.

Returns true if the given integer is an odd number, otherwise it returns false.

Allowed in guard clauses.

Examples

iex> Integer.is_odd(5)
true

iex> Integer.is_odd(6)
false

iex> Integer.is_odd(-5)
true

iex> Integer.is_odd(0)
false