# Integer

Class

Holds Integer values. You cannot add a singleton method to an Integer object, any attempt to do so will raise a TypeError.

Returns int modulo other.

Bitwise AND.

Performs multiplication: the class of the resulting object depends on the class of numeric.

Raises int to the power of numeric, which may be negative or fractional. The result may be an Integer, a Float, a Rational, or a complex number.

2 ** 3        #=> 8
2 ** -1       #=> (1/2)
2 ** 0.5      #=> 1.4142135623730951
(-1) ** 0.5   #=> (0.0+1.0i)

123456789 ** 2     #=> 15241578750190521
123456789 ** 1.2   #=> 5126464716.0993185
123456789 ** -2    #=> (1/15241578750190521)

Performs addition: the class of the resulting object depends on the class of numeric.

Performs subtraction: the class of the resulting object depends on the class of numeric.

Returns int, negated.

Performs division: the class of the resulting object depends on the class of numeric.

Returns true if the value of int is less than that of real.

Returns int shifted left count positions, or right if count is negative.

Returns true if the value of int is less than or equal to that of real.

Comparison—Returns -1, 0, or +1 depending on whether int is less than, equal to, or greater than numeric.

This is the basis for the tests in the Comparable module.

nil is returned if the two values are incomparable.

Returns true if int equals other numerically. Contrast this with Integer#eql?, which requires other to be an Integer.

1 == 2     #=> false
1 == 1.0   #=> true

Returns true if int equals other numerically. Contrast this with Integer#eql?, which requires other to be an Integer.

1 == 2     #=> false
1 == 1.0   #=> true

Returns true if the value of int is greater than that of real.

Returns true if the value of int is greater than or equal to that of real.

Returns int shifted right count positions, or left if count is negative.

Bit Reference—Returns the nth bit in the binary representation of int, where int[0] is the least significant bit.

a = 0b11001100101010
30.downto(0) {|n| print a[n] }
#=> 0000000000000000011001100101010

a = 9**15
50.downto(0) {|n| print a[n] }
#=> 000101110110100000111000011110010100111100010111001

In principle, n[i] is equivalent to (n >> i) & 1. Thus, any negative index always returns zero:

p 255[-1] #=> 0

Range operations n[i, len] and n[i..j] are naturally extended.

• n[i, len] equals to (n >> i) & ((1 << len) - 1).

• n[i..j] equals to (n >> i) & ((1 << (j - i + 1)) - 1).

• n[i...j] equals to (n >> i) & ((1 << (j - i)) - 1).

• n[i..] equals to (n >> i).

• n[..j] is zero if n & ((1 << (j + 1)) - 1) is zero. Otherwise, raises an ArgumentError.

• n[...j] is zero if n & ((1 << j) - 1) is zero. Otherwise, raises an ArgumentError.

Note that range operation may exhaust memory. For example, -1[0, 1000000000000] will raise NoMemoryError.

Bitwise EXCLUSIVE OR.

Returns the absolute value of int.

(-12345).abs   #=> 12345
-12345.abs     #=> 12345
12345.abs      #=> 12345

Integer#magnitude is an alias for Integer#abs.

Returns true if all bits of int & mask are 1.

Returns true if any bits of int & mask are 1.

Returns the number of bits of the value of int.

“Number of bits” means the bit position of the highest bit which is different from the sign bit (where the least significant bit has bit position 1). If there is no such bit (zero or minus one), zero is returned.

I.e. this method returns ceil(log2(int < 0 ? -int : int+1)).

(-2**1000-1).bit_length   #=> 1001
(-2**1000).bit_length     #=> 1000
(-2**1000+1).bit_length   #=> 1000
(-2**12-1).bit_length     #=> 13
(-2**12).bit_length       #=> 12
(-2**12+1).bit_length     #=> 12
-0x101.bit_length         #=> 9
-0x100.bit_length         #=> 8
-0xff.bit_length          #=> 8
-2.bit_length             #=> 1
-1.bit_length             #=> 0
0.bit_length              #=> 0
1.bit_length              #=> 1
0xff.bit_length           #=> 8
0x100.bit_length          #=> 9
(2**12-1).bit_length      #=> 12
(2**12).bit_length        #=> 13
(2**12+1).bit_length      #=> 13
(2**1000-1).bit_length    #=> 1000
(2**1000).bit_length      #=> 1001
(2**1000+1).bit_length    #=> 1001

This method can be used to detect overflow in Array#pack as follows:

if n.bit_length < 32
[n].pack("l") # no overflow
else
raise "overflow"
end

Returns the smallest number greater than or equal to int with a precision of ndigits decimal digits (default: 0).

When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.

Returns self when ndigits is zero or positive.

1.ceil           #=> 1
1.ceil(2)        #=> 1
18.ceil(-1)      #=> 20
(-18).ceil(-1)   #=> -10

Returns a string containing the character represented by the int's value according to encoding.

65.chr    #=> "A"
230.chr   #=> "\xE6"
255.chr(Encoding::UTF_8)   #=> "\u00FF"

Returns an array with both a numeric and a big represented as Bignum objects.

This is achieved by converting numeric to a Bignum.

A TypeError is raised if the numeric is not a Fixnum or Bignum type.

(0x3FFFFFFFFFFFFFFF+1).coerce(42)   #=> [42, 4611686018427387904]

Returns 1.

Returns the digits of int's place-value representation with radix base (default: 10). The digits are returned as an array with the least significant digit as the first array element.

base must be greater than or equal to 2.

12345.digits      #=> [5, 4, 3, 2, 1]
12345.digits(7)   #=> [4, 6, 6, 0, 5]
12345.digits(100) #=> [45, 23, 1]

-12345.digits(7)  #=> Math::DomainError

Performs integer division: returns the integer result of dividing int by numeric.

Iterates the given block, passing in decreasing values from int down to and including limit.

If no block is given, an Enumerator is returned instead.

5.downto(1) { |n| print n, ".. " }
puts "Liftoff!"
#=> "5.. 4.. 3.. 2.. 1.. Liftoff!"

#### each_prime

Iterates the given block over all prime numbers.

See Prime#each for more details.

Returns true if int is an even number.

Returns the floating point result of dividing int by numeric.

654321.fdiv(13731)      #=> 47.652829364212366
654321.fdiv(13731.24)   #=> 47.65199646936475
-654321.fdiv(13731)     #=> -47.652829364212366

Returns the largest number less than or equal to int with a precision of ndigits decimal digits (default: 0).

When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.

Returns self when ndigits is zero or positive.

1.floor           #=> 1
1.floor(2)        #=> 1
18.floor(-1)      #=> 10
(-18).floor(-1)   #=> -20

#### from_prime_division

Re-composes a prime factorization and returns the product.

See Prime#int_from_prime_division for more details.

Returns the greatest common divisor of the two integers. The result is always positive. 0.gcd(x) and x.gcd(0) return x.abs.

36.gcd(60)                  #=> 12
2.gcd(2)                    #=> 2
3.gcd(-7)                   #=> 1
((1<<31)-1).gcd((1<<61)-1)  #=> 1

Returns an array with the greatest common divisor and the least common multiple of the two integers, [gcd, lcm].

36.gcdlcm(60)                  #=> [12, 180]
2.gcdlcm(2)                    #=> [2, 2]
3.gcdlcm(-7)                   #=> [1, 21]
((1<<31)-1).gcdlcm((1<<61)-1)  #=> [1, 4951760154835678088235319297]

#### inspect

No documentation available

Since int is already an Integer, this always returns true.

Returns the least common multiple of the two integers. The result is always positive. 0.lcm(x) and x.lcm(0) return zero.

36.lcm(60)                  #=> 180
2.lcm(2)                    #=> 2
3.lcm(-7)                   #=> 21
((1<<31)-1).lcm((1<<61)-1)  #=> 4951760154835678088235319297

Returns the absolute value of int.

(-12345).abs   #=> 12345
-12345.abs     #=> 12345
12345.abs      #=> 12345

Integer#magnitude is an alias for Integer#abs.

Returns int modulo other.

Returns the successor of int, i.e. the Integer equal to int+1.

1.next      #=> 2
(-1).next   #=> 0
1.succ      #=> 2
(-1).succ   #=> 0

Returns true if no bits of int & mask are 1.

Returns self.

Returns true if int is an odd number.

Returns the int itself.

97.ord   #=> 97

This method is intended for compatibility to character literals in Ruby 1.9.

For example, ?a.ord returns 97 both in 1.8 and 1.9.

Returns (modular) exponentiation as:

a.pow(b)     #=> same as a**b
a.pow(b, m)  #=> same as (a**b) % m, but avoids huge temporary values

Returns the predecessor of int, i.e. the Integer equal to int-1.

1.pred      #=> 0
(-1).pred   #=> -2

#### prime?

Returns true if self is a prime number, else returns false.

#### prime_division

Returns the factorization of self.

See Prime#prime_division for more details.

Returns the value as a rational. The optional argument eps is always ignored.

Returns the remainder after dividing int by numeric.

x.remainder(y) means x-y*(x/y).truncate.

5.remainder(3)     #=> 2
-5.remainder(3)    #=> -2
5.remainder(-3)    #=> 2
-5.remainder(-3)   #=> -2
5.remainder(1.5)   #=> 0.5

See Numeric#divmod.

Returns int rounded to the nearest value with a precision of ndigits decimal digits (default: 0).

When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.

Returns self when ndigits is zero or positive.

1.round           #=> 1
1.round(2)        #=> 1
15.round(-1)      #=> 20
(-15).round(-1)   #=> -20

The optional half keyword argument is available similar to Float#round.

25.round(-1, half: :up)      #=> 30
25.round(-1, half: :down)    #=> 20
25.round(-1, half: :even)    #=> 20
35.round(-1, half: :up)      #=> 40
35.round(-1, half: :down)    #=> 30
35.round(-1, half: :even)    #=> 40
(-25).round(-1, half: :up)   #=> -30
(-25).round(-1, half: :down) #=> -20
(-25).round(-1, half: :even) #=> -20

Returns the number of bytes in the machine representation of int (machine dependent).

1.size               #=> 8
-1.size              #=> 8
2147483647.size      #=> 8
(256**10 - 1).size   #=> 10
(256**20 - 1).size   #=> 20
(256**40 - 1).size   #=> 40

Returns the integer square root of the non-negative integer n, i.e. the largest non-negative integer less than or equal to the square root of n.

Integer.sqrt(0)        #=> 0
Integer.sqrt(1)        #=> 1
Integer.sqrt(24)       #=> 4
Integer.sqrt(25)       #=> 5
Integer.sqrt(10**400)  #=> 10**200

Equivalent to Math.sqrt(n).floor, except that the result of the latter code may differ from the true value due to the limited precision of floating point arithmetic.

Integer.sqrt(10**46)     #=> 100000000000000000000000
Math.sqrt(10**46).floor  #=>  99999999999999991611392 (!)

If n is not an Integer, it is converted to an Integer first. If n is negative, a Math::DomainError is raised.

Returns the successor of int, i.e. the Integer equal to int+1.

1.next      #=> 2
(-1).next   #=> 0
1.succ      #=> 2
(-1).succ   #=> 0

Iterates the given block int times, passing in values from zero to int - 1.

If no block is given, an Enumerator is returned instead.

5.times {|i| print i, " " }   #=> 0 1 2 3 4

#### to_bn

Casts an Integer as an OpenSSL::BN

Returns the value of int as a BigDecimal.

require 'bigdecimal'
require 'bigdecimal/util'

42.to_d   # => 0.42e2

Converts int to a Float. If int doesn't fit in a Float, the result is infinity.

Since int is already an Integer, returns self.

to_int is an alias for to_i.

Since int is already an Integer, returns self.

to_int is an alias for to_i.

Returns the value as a rational.

1.to_r        #=> (1/1)
(1<<64).to_r  #=> (18446744073709551616/1)

Returns a string containing the place-value representation of int with radix base (between 2 and 36).

12345.to_s       #=> "12345"
12345.to_s(2)    #=> "11000000111001"
12345.to_s(8)    #=> "30071"
12345.to_s(10)   #=> "12345"
12345.to_s(16)   #=> "3039"
12345.to_s(36)   #=> "9ix"
78546939656932.to_s(36)  #=> "rubyrules"

Returns int truncated (toward zero) to a precision of ndigits decimal digits (default: 0).

When the precision is negative, the returned value is an integer with at least ndigits.abs trailing zeros.

Returns self when ndigits is zero or positive.

1.truncate           #=> 1
1.truncate(2)        #=> 1
18.truncate(-1)      #=> 10
(-18).truncate(-1)   #=> -10

Iterates the given block, passing in integer values from int up to and including limit.

If no block is given, an Enumerator is returned instead.

5.upto(10) {|i| print i, " " }   #=> 5 6 7 8 9 10

Bitwise OR.

One's complement: returns a number where each bit is flipped.

Inverts the bits in an Integer. As integers are conceptually of infinite length, the result acts as if it had an infinite number of one bits to the left. In hex representations, this is displayed as two periods to the left of the digits.

sprintf("%X", ~0x1122334455)    #=> "..FEEDDCCBBAA"