class Integer - RDoc Documentation

# class Integer

An Integer object represents an integer value.

You can create an Integer object explicitly with:

- An integer literal.

You can convert certain objects to Integers with:

- Method Integer.

An attempt to add a singleton method to an instance of this class causes an exception to be raised.

## What’s Here¶ ↑

First, what’s elsewhere. Class Integer:

- Inherits from class Numeric.

Here, class Integer provides methods for:

- Querying

- Comparing

- Converting

- Other

### Querying¶ ↑

- `allbits?`

    Returns whether all bits in `self` are set.

- `anybits?`

    Returns whether any bits in `self` are set.

- `nobits?`

    Returns whether no bits in `self` are set.

### Comparing¶ ↑

- <

    Returns whether `self` is less than the given value.

- <=

    Returns whether `self` is less than or equal to the given value.

- <=>

    Returns a number indicating whether `self` is less than, equal to, or greater than the given value.

- == (aliased as `===`)

    Returns whether `self` is equal to the given value.

- >

    Returns whether `self` is greater than the given value.

- >=

    Returns whether `self` is greater than or equal to the given value.

### Converting¶ ↑

- `::sqrt`

    Returns the integer square root of the given value.

- `::try_convert`

    Returns the given value converted to an Integer.

- `%` (aliased as `modulo`)

    Returns `self` modulo the given value.

- &

    Returns the bitwise AND of `self` and the given value.

- `*`

    Returns the product of `self` and the given value.

- **

    Returns the value of `self` raised to the power of the given value.

- `+`

    Returns the sum of `self` and the given value.

- `-`

    Returns the difference of `self` and the given value.

- /

    Returns the quotient of `self` and the given value.

- `<<`

    Returns the value of `self` after a leftward bit-shift.

- `>>`

    Returns the value of `self` after a rightward bit-shift.

- `[]`

    Returns a slice of bits from `self`.

- ^

    Returns the bitwise EXCLUSIVE OR of `self` and the given value.

- `ceil`

    Returns the smallest number greater than or equal to `self`.

- `chr`

    Returns a 1-character string containing the character represented by the value of `self`.

- `digits`

    Returns an array of integers representing the base-radix digits of `self`.

- `div`

    Returns the integer result of dividing `self` by the given value.

- `divmod`

    Returns a 2-element array containing the quotient and remainder results of dividing `self` by the given value.

- `fdiv`

    Returns the `Float` result of dividing `self` by the given value.

- `floor`

    Returns the greatest number smaller than or equal to `self`.

- `pow`

    Returns the modular exponentiation of `self`.

- `pred`

    Returns the integer predecessor of `self`.

- `remainder`

    Returns the remainder after dividing `self` by the given value.

- `round`

    Returns `self` rounded to the nearest value with the given precision.

- `succ` (aliased as `next`)

    Returns the integer successor of `self`.

- `to_f`

    Returns `self` converted to a `Float`.

- `to_s` (aliased as `inspect`)

    Returns a string containing the place-value representation of `self` in the given radix.

- `truncate`

    Returns `self` truncated to the given precision.

- /

    Returns the bitwise OR of `self` and the given value.

### Other¶ ↑

- `downto`

    Calls the given block with each integer value from `self` down to the given value.

- `times`

    Calls the given block `self` times with each integer in `(0..self-1)`.

- `upto`

    Calls the given block with each integer value from `self` up to the given value.

### Constants

GMP_VERSION

  The version of loaded GMP.

### Public Class Methods

sqrt(numeric) → integer click to toggle source

Returns the integer square root of the non-negative integer `n`, which is the largest non-negative integer less than or equal to the square root of `numeric`.

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

If `numeric` is not an Integer, it is converted to an Integer:

    Integer.sqrt(Complex(4, 0))  # => 2
    Integer.sqrt(Rational(4, 1)) # => 2
    Integer.sqrt(4.0)            # => 2
    Integer.sqrt(3.14159)        # => 1

This method is equivalent to `Math.sqrt(numeric).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

Raises an exception if `numeric` is negative.

    static VALUE
    rb_int_s_isqrt(VALUE self, VALUE num)
    {
        unsigned long n, sq;
        num = rb_to_int(num);
        if (FIXNUM_P(num)) {
            if (FIXNUM_NEGATIVE_P(num)) {
                domain_error("isqrt");
            }
            n = FIX2ULONG(num);
            sq = rb_ulong_isqrt(n);
            return LONG2FIX(sq);
        }
        else {
            size_t biglen;
            if (RBIGNUM_NEGATIVE_P(num)) {
                domain_error("isqrt");
            }
            biglen = BIGNUM_LEN(num);
            if (biglen == 0) return INT2FIX(0);
    #if SIZEOF_BDIGIT <= SIZEOF_LONG
            /* short-circuit */
            if (biglen == 1) {
                n = BIGNUM_DIGITS(num)[0];
                sq = rb_ulong_isqrt(n);
                return ULONG2NUM(sq);
            }
    #endif
            return rb_big_isqrt(num);
        }
    }

try_convert(object) → object, integer, or nil click to toggle source

If `object` is an Integer object, returns `object`.

    Integer.try_convert(1) # => 1

Otherwise if `object` responds to `:to_int`, calls `object.to_int` and returns the result.

    Integer.try_convert(1.25) # => 1

Returns `nil` if `object` does not respond to `:to_int`

    Integer.try_convert([]) # => nil

Raises an exception unless `object.to_int` returns an Integer object.

    # File numeric.rb, line 247
    def Integer.try_convert(num)
    =begin
      Primitive.attr! 'inline'
      Primitive.cexpr! 'rb_check_integer_type(num)'
    =end
    end

### Public Instance Methods

self % other → real_number click to toggle source

Returns `self` modulo `other` as a real number.

For integer `n` and real number `r`, these expressions are equivalent:

    n % r
    n-r*(n/r).floor
    n.divmod(r)[1]

See `Numeric#divmod`.

Examples:

    10 % 2              # => 0
    10 % 3              # => 1
    10 % 4              # => 2

    10 % -2             # => 0
    10 % -3             # => -2
    10 % -4             # => -2

    10 % 3.0            # => 1.0
    10 % Rational(3, 1) # => (1/1)

`Integer#modulo` is an alias for `Integer#%`.

    VALUE
    rb_int_modulo(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_mod(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_modulo(x, y);
        }
        return num_modulo(x, y);
    }

Also aliased as: modulo
self & other → integer click to toggle source

Bitwise AND; each bit in the result is 1 if both corresponding bits in `self` and `other` are 1, 0 otherwise:

    "%04b" % (0b0101 & 0b0110) # => "0100"

Raises an exception if `other` is not an Integer.

Related: Integer#| (bitwise OR), Integer#^ (bitwise EXCLUSIVE OR).

    VALUE
    rb_int_and(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_and(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_and(x, y);
        }
        return Qnil;
    }

self * numeric → numeric_result click to toggle source

Performs multiplication:

    4 * 2              # => 8
    4 * -2             # => -8
    -4 * 2             # => -8
    4 * 2.0            # => 8.0
    4 * Rational(1, 3) # => (4/3)
    4 * Complex(2, 0)  # => (8+0i)

    VALUE
    rb_int_mul(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_mul(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_mul(x, y);
        }
        return rb_num_coerce_bin(x, y, '*');
    }

self ** numeric → numeric_result click to toggle source

Raises `self` to the power of `numeric`:

    2 ** 3              # => 8
    2 ** -3             # => (1/8)
    -2 ** 3             # => -8
    -2 ** -3            # => (-1/8)
    2 ** 3.3            # => 9.849155306759329
    2 ** Rational(3, 1) # => (8/1)
    2 ** Complex(3, 0)  # => (8+0i)

    VALUE
    rb_int_pow(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_pow(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_pow(x, y);
        }
        return Qnil;
    }

self + numeric → numeric_result click to toggle source

Performs addition:

    2 + 2              # => 4
    -2 + 2             # => 0
    -2 + -2            # => -4
    2 + 2.0            # => 4.0
    2 + Rational(2, 1) # => (4/1)
    2 + Complex(2, 0)  # => (4+0i)

    VALUE
    rb_int_plus(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_plus(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_plus(x, y);
        }
        return rb_num_coerce_bin(x, y, '+');
    }

self - numeric → numeric_result click to toggle source

Performs subtraction:

    4 - 2              # => 2
    -4 - 2             # => -6
    -4 - -2            # => -2
    4 - 2.0            # => 2.0
    4 - Rational(2, 1) # => (2/1)
    4 - Complex(2, 0)  # => (2+0i)

    VALUE
    rb_int_minus(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_minus(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_minus(x, y);
        }
        return rb_num_coerce_bin(x, y, '-');
    }

-int → integer click to toggle source

Returns `int`, negated.

    # File numeric.rb, line 52
    def -@
      Primitive.attr! 'inline'
      Primitive.cexpr! 'rb_int_uminus(self)'
    end

self / numeric → numeric_result click to toggle source

Performs division; for integer `numeric`, truncates the result to an integer:

     4 / 3              # => 1
     4 / -3             # => -2
     -4 / 3             # => -2
     -4 / -3            # => 1

    For other +numeric+, returns non-integer result:

     4 / 3.0            # => 1.3333333333333333
     4 / Rational(3, 1) # => (4/3)
     4 / Complex(3, 0)  # => ((4/3)+0i)

    VALUE
    rb_int_div(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_div(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_div(x, y);
        }
        return Qnil;
    }

self < other → true or false click to toggle source

Returns `true` if the value of `self` is less than that of `other`:

      1 < 0              # => false
      1 < 1              # => false
      1 < 2              # => true
      1 < 0.5            # => false
      1 < Rational(1, 2) # => false

    Raises an exception if the comparison cannot be made.

    static VALUE
    int_lt(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_lt(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_lt(x, y);
        }
        return Qnil;
    }

self << count → integer click to toggle source

Returns `self` with bits shifted `count` positions to the left, or to the right if `count` is negative:

    n = 0b11110000
    "%08b" % (n << 1)  # => "111100000"
    "%08b" % (n << 3)  # => "11110000000"
    "%08b" % (n << -1) # => "01111000"
    "%08b" % (n << -3) # => "00011110"

Related: `Integer#>>`.

    VALUE
    rb_int_lshift(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return rb_fix_lshift(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_lshift(x, y);
        }
        return Qnil;
    }

self <= real → true or false click to toggle source

Returns `true` if the value of `self` is less than or equal to that of `other`:

    1 <= 0              # => false
    1 <= 1              # => true
    1 <= 2              # => true
    1 <= 0.5            # => false
    1 <= Rational(1, 2) # => false

Raises an exception if the comparison cannot be made.

    static VALUE
    int_le(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_le(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_le(x, y);
        }
        return Qnil;
    }

self <=> other → -1, 0, +1, or nil click to toggle source

Returns:

- -1, if `self` is less than `other`.

- 0, if `self` is equal to `other`.

- 1, if `self` is greater then `other`.

- `nil`, if `self` and `other` are incomparable.

Examples:

    1 <=> 2              # => -1
    1 <=> 1              # => 0
    1 <=> 0              # => 1
    1 <=> 'foo'          # => nil

    1 <=> 1.0            # => 0
    1 <=> Rational(1, 1) # => 0
    1 <=> Complex(1, 0)  # => 0

This method is the basis for comparisons in module `Comparable`.

    VALUE
    rb_int_cmp(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_cmp(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_cmp(x, y);
        }
        else {
            rb_raise(rb_eNotImpError, "need to define `<=>' in %s", rb_obj_classname(x));
        }
    }

self == other → true or false

Returns `true` if `self` is numerically equal to `other`; `false` otherwise.

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

Related: `Integer#eql?` (requires `other` to be an Integer).

`Integer#===` is an alias for `Integer#==`.

Alias for: ===
=== == other -> true or false click to toggle source

Returns `true` if `self` is numerically equal to `other`; `false` otherwise.

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

Related: `Integer#eql?` (requires `other` to be an Integer).

`Integer#===` is an alias for `Integer#==`.

    VALUE
    rb_int_equal(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_equal(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_eq(x, y);
        }
        return Qnil;
    }

Also aliased as: ==
self > other → true or false click to toggle source

Returns `true` if the value of `self` is greater than that of `other`:

      1 > 0              # => true
      1 > 1              # => false
      1 > 2              # => false
      1 > 0.5            # => true
      1 > Rational(1, 2) # => true

    Raises an exception if the comparison cannot be made.

    VALUE
    rb_int_gt(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_gt(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_gt(x, y);
        }
        return Qnil;
    }

self >= real → true or false click to toggle source

Returns `true` if the value of `self` is greater than or equal to that of `other`:

    1 >= 0              # => true
    1 >= 1              # => true
    1 >= 2              # => false
    1 >= 0.5            # => true
    1 >= Rational(1, 2) # => true

Raises an exception if the comparison cannot be made.

    VALUE
    rb_int_ge(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_ge(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_ge(x, y);
        }
        return Qnil;
    }

self >> count → integer click to toggle source

Returns `self` with bits shifted `count` positions to the right, or to the left if `count` is negative:

    n = 0b11110000
    "%08b" % (n >> 1)  # => "01111000"
    "%08b" % (n >> 3)  # => "00011110"
    "%08b" % (n >> -1) # => "111100000"
    "%08b" % (n >> -3) # => "11110000000"

Related: `Integer#<<`.

    static VALUE
    rb_int_rshift(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return rb_fix_rshift(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_rshift(x, y);
        }
        return Qnil;
    }

self[offset] → 0 or 1 click to toggle source
self[offset, size] → integer
self[range] → integer

Returns a slice of bits from `self`.

With argument `offset`, returns the bit at the given offset, where offset 0 refers to the least significant bit:

    n = 0b10 # => 2
    n[0]     # => 0
    n[1]     # => 1
    n[2]     # => 0
    n[3]     # => 0

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

    255[-1] # => 0

With arguments `offset` and `size`, returns `size` bits from `self`, beginning at `offset` and including bits of greater significance:

    n = 0b111000       # => 56
    "%010b" % n[0, 10] # => "0000111000"
    "%010b" % n[4, 10] # => "0000000011"

With argument `range`, returns `range.size` bits from `self`, beginning at `range.begin` and including bits of greater significance:

    n = 0b111000      # => 56
    "%010b" % n[0..9] # => "0000111000"
    "%010b" % n[4..9] # => "0000000011"

Raises an exception if the slice cannot be constructed.

    static VALUE
    int_aref(int const argc, VALUE * const argv, VALUE const num)
    {
        rb_check_arity(argc, 1, 2);
        if (argc == 2) {
            return int_aref2(num, argv[0], argv[1]);
        }
        return int_aref1(num, argv[0]);

        return Qnil;
    }

self ^ other → integer click to toggle source

Bitwise EXCLUSIVE OR; each bit in the result is 1 if the corresponding bits in `self` and `other` are different, 0 otherwise:

    "%04b" % (0b0101 ^ 0b0110) # => "0011"

Raises an exception if `other` is not an Integer.

Related: Integer#& (bitwise AND), Integer#| (bitwise OR).

    static VALUE
    int_xor(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_xor(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_xor(x, y);
        }
        return Qnil;
    }

abs → integer click to toggle source

Returns the absolute value of `int`.

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

`Integer#magnitude` is an alias for `Integer#abs`.

    # File numeric.rb, line 84
    def abs
      Primitive.attr! 'inline'
      Primitive.cexpr! 'rb_int_abs(self)'
    end

Also aliased as: magnitude
allbits?(mask) → true or false click to toggle source

Returns `true` if all bits that are set (=1) in `mask` are also set in `self`; returns `false` otherwise.

Example values:

    0b1010101  self
    0b1010100  mask
    0b1010100  self & mask
         true  self.allbits?(mask)

    0b1010100  self
    0b1010101  mask
    0b1010100  self & mask
        false  self.allbits?(mask)

Related: `Integer#anybits?`, `Integer#nobits?`.

    static VALUE
    int_allbits_p(VALUE num, VALUE mask)
    {
        mask = rb_to_int(mask);
        return rb_int_equal(rb_int_and(num, mask), mask);
    }

anybits?(mask) → true or false click to toggle source

Returns `true` if any bit that is set (=1) in `mask` is also set in `self`; returns `false` otherwise.

Example values:

    0b10000010  self
    0b11111111  mask
    0b10000010  self & mask
          true  self.anybits?(mask)

    0b00000000  self
    0b11111111  mask
    0b00000000  self & mask
         false  self.anybits?(mask)

Related: `Integer#allbits?`, `Integer#nobits?`.

    static VALUE
    int_anybits_p(VALUE num, VALUE mask)
    {
        mask = rb_to_int(mask);
        return int_zero_p(rb_int_and(num, mask)) ? Qfalse : Qtrue;
    }

bit_length → integer click to toggle source

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

    # File numeric.rb, line 130
    def bit_length
      Primitive.attr! 'inline'
      Primitive.cexpr! 'rb_int_bit_length(self)'
    end

ceil(ndigits = 0) → integer click to toggle source

Returns the smallest number greater than or equal to `self` with a precision of `ndigits` decimal digits.

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

    555.ceil(-1)  # => 560
    555.ceil(-2)  # => 600
    -555.ceil(-2) # => -500
    555.ceil(-3)  # => 1000

Returns `self` when `ndigits` is zero or positive.

    555.ceil     # => 555
    555.ceil(50) # => 555

Related: `Integer#floor`.

    static VALUE
    int_ceil(int argc, VALUE* argv, VALUE num)
    {
        int ndigits;

        if (!rb_check_arity(argc, 0, 1)) return num;
        ndigits = NUM2INT(argv[0]);
        if (ndigits >= 0) {
            return num;
        }
        return rb_int_ceil(num, ndigits);
    }

chr → string click to toggle source
chr(encoding) → string

Returns a 1-character string containing the character represented by the value of `self`, according to the given `encoding`.

    65.chr                   # => "A"
    0..chr                   # => "\x00"
    255.chr                  # => "\xFF"
    string = 255.chr(Encoding::UTF_8)
    string.encoding          # => Encoding::UTF_8

Raises an exception if `self` is negative.

Related: `Integer#ord`.

    static VALUE
    int_chr(int argc, VALUE *argv, VALUE num)
    {
        char c;
        unsigned int i;
        rb_encoding *enc;

        if (rb_num_to_uint(num, &i) == 0) {
        }
        else if (FIXNUM_P(num)) {
            rb_raise(rb_eRangeError, "%ld out of char range", FIX2LONG(num));
        }
        else {
            rb_raise(rb_eRangeError, "bignum out of char range");
        }

        switch (argc) {
          case 0:
            if (0xff < i) {
                enc = rb_default_internal_encoding();
                if (!enc) {
                    rb_raise(rb_eRangeError, "%u out of char range", i);
                }
                goto decode;
            }
            c = (char)i;
            if (i < 0x80) {
                return rb_usascii_str_new(&c, 1);
            }
            else {
                return rb_str_new(&c, 1);
            }
          case 1:
            break;
          default:
            rb_error_arity(argc, 0, 1);
        }
        enc = rb_to_encoding(argv[0]);
        if (!enc) enc = rb_ascii8bit_encoding();
      decode:
        return rb_enc_uint_chr(i, enc);
    }

coerce(numeric) → array click to toggle source

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]

    static VALUE
    rb_int_coerce(VALUE x, VALUE y)
    {
        if (RB_INTEGER_TYPE_P(y)) {
            return rb_assoc_new(y, x);
        }
        else {
            x = rb_Float(x);
            y = rb_Float(y);
            return rb_assoc_new(y, x);
        }
    }

denominator → 1 click to toggle source

Returns 1.

    static VALUE
    integer_denominator(VALUE self)
    {
        return INT2FIX(1);
    }

digits(base = 10) → array_of_integers click to toggle source

Returns an array of integers representing the `base`-radix digits of `self`; the first element of the array represents the least significant digit:

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

Raises an exception if `self` is negative or `base` is less than 2.

    static VALUE
    rb_int_digits(int argc, VALUE *argv, VALUE num)
    {
        VALUE base_value;
        long base;

        if (rb_num_negative_p(num))
            rb_raise(rb_eMathDomainError, "out of domain");

        if (rb_check_arity(argc, 0, 1)) {
            base_value = rb_to_int(argv[0]);
            if (!RB_INTEGER_TYPE_P(base_value))
                rb_raise(rb_eTypeError, "wrong argument type %s (expected Integer)",
                         rb_obj_classname(argv[0]));
            if (RB_BIGNUM_TYPE_P(base_value))
                return rb_int_digits_bigbase(num, base_value);

            base = FIX2LONG(base_value);
            if (base < 0)
                rb_raise(rb_eArgError, "negative radix");
            else if (base < 2)
                rb_raise(rb_eArgError, "invalid radix %ld", base);
        }
        else
            base = 10;

        if (FIXNUM_P(num))
            return rb_fix_digits(num, base);
        else if (RB_BIGNUM_TYPE_P(num))
            return rb_int_digits_bigbase(num, LONG2FIX(base));

        return Qnil;
    }

div(numeric) → integer click to toggle source

Performs integer division; returns the integer result of dividing `self` by `numeric`:

      4.div(3)      # => 1
      4.div(-3)      # => -2
      -4.div(3)      # => -2
      -4.div(-3)      # => 1
      4.div(3.0)      # => 1
      4.div(Rational(3, 1))      # => 1

    Raises an exception if +numeric+ does not have method +div+.

    VALUE
    rb_int_idiv(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_idiv(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_idiv(x, y);
        }
        return num_div(x, y);
    }

divmod(other) → array click to toggle source

Returns a 2-element array `[q, r]`, where

    q = (self/other).floor    # Quotient
    r = self % other          # Remainder

Examples:

    11.divmod(4)              # => [2, 3]
    11.divmod(-4)             # => [-3, -1]
    -11.divmod(4)             # => [-3, 1]
    -11.divmod(-4)            # => [2, -3]

    12.divmod(4)              # => [3, 0]
    12.divmod(-4)             # => [-3, 0]
    -12.divmod(4)             # => [-3, 0]
    -12.divmod(-4)            # => [3, 0]

    13.divmod(4.0)            # => [3, 1.0]
    13.divmod(Rational(4, 1)) # => [3, (1/1)]

    VALUE
    rb_int_divmod(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_divmod(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_divmod(x, y);
        }
        return Qnil;
    }

downto(limit) {|i| ... } → self click to toggle source
downto(limit) → enumerator

Calls the given block with each integer value from `self` down to `limit`; returns `self`:

    a = []
    10.downto(5) {|i| a << i }              # => 10
    a                                       # => [10, 9, 8, 7, 6, 5]
    a = []
    0.downto(-5) {|i| a << i }              # => 0
    a                                       # => [0, -1, -2, -3, -4, -5]
    4.downto(5) {|i| fail 'Cannot happen' } # => 4

With no block given, returns an `Enumerator`.

    static VALUE
    int_downto(VALUE from, VALUE to)
    {
        RETURN_SIZED_ENUMERATOR(from, 1, &to, int_downto_size);
        if (FIXNUM_P(from) && FIXNUM_P(to)) {
            long i, end;

            end = FIX2LONG(to);
            for (i=FIX2LONG(from); i >= end; i--) {
                rb_yield(LONG2FIX(i));
            }
        }
        else {
            VALUE i = from, c;

            while (!(c = rb_funcall(i, '<', 1, to))) {
                rb_yield(i);
                i = rb_funcall(i, '-', 1, INT2FIX(1));
            }
            if (NIL_P(c)) rb_cmperr(i, to);
        }
        return from;
    }

even? → true or false click to toggle source

Returns `true` if `int` is an even number.

    # File numeric.rb, line 139
    def even?
      Primitive.attr! 'inline'
      Primitive.cexpr! 'rb_int_even_p(self)'
    end

fdiv(numeric) → float click to toggle source

Returns the `Float` result of dividing `self` by `numeric`:

    4.fdiv(2)      # => 2.0
    4.fdiv(-2)      # => -2.0
    -4.fdiv(2)      # => -2.0
    4.fdiv(2.0)      # => 2.0
    4.fdiv(Rational(3, 4))      # => 5.333333333333333

Raises an exception if `numeric` cannot be converted to a `Float`.

    VALUE
    rb_int_fdiv(VALUE x, VALUE y)
    {
        if (RB_INTEGER_TYPE_P(x)) {
            return DBL2NUM(rb_int_fdiv_double(x, y));
        }
        return Qnil;
    }

floor(ndigits = 0) → integer click to toggle source

Returns the largest number less than or equal to `self` with a precision of `ndigits` decimal digits.

When `ndigits` is negative, the returned value has at least `ndigits.abs` trailing zeros:

    555.floor(-1)  # => 550
    555.floor(-2)  # => 500
    -555.floor(-2) # => -600
    555.floor(-3)  # => 0

Returns `self` when `ndigits` is zero or positive.

    555.floor     # => 555
    555.floor(50) # => 555

Related: `Integer#ceil`.

    static VALUE
    int_floor(int argc, VALUE* argv, VALUE num)
    {
        int ndigits;

        if (!rb_check_arity(argc, 0, 1)) return num;
        ndigits = NUM2INT(argv[0]);
        if (ndigits >= 0) {
            return num;
        }
        return rb_int_floor(num, ndigits);
    }

gcd(other_int) → integer click to toggle source

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

    VALUE
    rb_gcd(VALUE self, VALUE other)
    {
        other = nurat_int_value(other);
        return f_gcd(self, other);
    }

gcdlcm(other_int) → array click to toggle source

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]

    VALUE
    rb_gcdlcm(VALUE self, VALUE other)
    {
        other = nurat_int_value(other);
        return rb_assoc_new(f_gcd(self, other), f_lcm(self, other));
    }

inspect(*args)

Returns a string containing the place-value representation of `self` in radix `base` (in 2..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"

Raises an exception if `base` is out of range.

`Integer#inspect` is an alias for `Integer#to_s`.

Alias for: to_s
integer? → true click to toggle source

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

    # File numeric.rb, line 148
    def integer?
      return true
    end

lcm(other_int) → integer click to toggle source

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

    VALUE
    rb_lcm(VALUE self, VALUE other)
    {
        other = nurat_int_value(other);
        return f_lcm(self, other);
    }

magnitude → integer
Alias for: abs
modulo(p1)

Returns `self` modulo `other` as a real number.

For integer `n` and real number `r`, these expressions are equivalent:

    n % r
    n-r*(n/r).floor
    n.divmod(r)[1]

See `Numeric#divmod`.

Examples:

    10 % 2              # => 0
    10 % 3              # => 1
    10 % 4              # => 2

    10 % -2             # => 0
    10 % -3             # => -2
    10 % -4             # => -2

    10 % 3.0            # => 1.0
    10 % Rational(3, 1) # => (1/1)

`Integer#modulo` is an alias for `Integer#%`.

Alias for: %
next()

Returns the successor integer of `self` (equivalent to `self + 1`):

    1.succ  #=> 2
    -1.succ #=> 0

`Integer#next` is an alias for `Integer#succ`.

Related: `Integer#pred` (predecessor value).

Alias for: succ
nobits?(mask) → true or false click to toggle source

Returns `true` if no bit that is set (=1) in `mask` is also set in `self`; returns `false` otherwise.

Example values:

    0b11110000  self
    0b00001111  mask
    0b00000000  self & mask
          true  self.nobits?(mask)

    0b00000001  self
    0b11111111  mask
    0b00000001  self & mask
         false  self.nobits?(mask)

Related: `Integer#allbits?`, `Integer#anybits?`.

    static VALUE
    int_nobits_p(VALUE num, VALUE mask)
    {
        mask = rb_to_int(mask);
        return int_zero_p(rb_int_and(num, mask));
    }

numerator → self click to toggle source

Returns self.

    static VALUE
    integer_numerator(VALUE self)
    {
        return self;
    }

odd? → true or false click to toggle source

Returns `true` if `int` is an odd number.

    # File numeric.rb, line 164
    def odd?
      Primitive.attr! 'inline'
      Primitive.cexpr! 'rb_int_odd_p(self)'
    end

ord → self click to toggle source

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.

    # File numeric.rb, line 180
    def ord
      return self
    end

pow(numeric) → numeric click to toggle source
pow(integer, integer) → integer

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

    VALUE
    rb_int_powm(int const argc, VALUE * const argv, VALUE const num)
    {
        rb_check_arity(argc, 1, 2);

        if (argc == 1) {
            return rb_int_pow(num, argv[0]);
        }
        else {
            VALUE const a = num;
            VALUE const b = argv[0];
            VALUE m = argv[1];
            int nega_flg = 0;
            if ( ! RB_INTEGER_TYPE_P(b)) {
                rb_raise(rb_eTypeError, "Integer#pow() 2nd argument not allowed unless a 1st argument is integer");
            }
            if (rb_int_negative_p(b)) {
                rb_raise(rb_eRangeError, "Integer#pow() 1st argument cannot be negative when 2nd argument specified");
            }
            if (!RB_INTEGER_TYPE_P(m)) {
                rb_raise(rb_eTypeError, "Integer#pow() 2nd argument not allowed unless all arguments are integers");
            }

            if (rb_int_negative_p(m)) {
                m = rb_int_uminus(m);
                nega_flg = 1;
            }

            if (FIXNUM_P(m)) {
                long const half_val = (long)HALF_LONG_MSB;
                long const mm = FIX2LONG(m);
                if (!mm) rb_num_zerodiv();
                if (mm == 1) return INT2FIX(0);
                if (mm <= half_val) {
                    return int_pow_tmp1(rb_int_modulo(a, m), b, mm, nega_flg);
                }
                else {
                    return int_pow_tmp2(rb_int_modulo(a, m), b, mm, nega_flg);
                }
            }
            else {
                if (rb_bigzero_p(m)) rb_num_zerodiv();
    	    if (bignorm(m) == INT2FIX(1)) return INT2FIX(0);
                return int_pow_tmp3(rb_int_modulo(a, m), b, m, nega_flg);
            }
        }
        UNREACHABLE_RETURN(Qnil);
    }

pred → next_integer click to toggle source

Returns the predecessor of `self` (equivalent to `self - 1`):

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

Related: `Integer#succ` (successor value).

    static VALUE
    rb_int_pred(VALUE num)
    {
        if (FIXNUM_P(num)) {
            long i = FIX2LONG(num) - 1;
            return LONG2NUM(i);
        }
        if (RB_BIGNUM_TYPE_P(num)) {
            return rb_big_minus(num, INT2FIX(1));
        }
        return num_funcall1(num, '-', INT2FIX(1));
    }

rationalize([eps]) → rational click to toggle source

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

    static VALUE
    integer_rationalize(int argc, VALUE *argv, VALUE self)
    {
        rb_check_arity(argc, 0, 1);
        return integer_to_r(self);
    }

remainder(other) → real_number click to toggle source

Returns the remainder after dividing `self` by `other`.

Examples:

    11.remainder(4)              # => 3
    11.remainder(-4)             # => 3
    -11.remainder(4)             # => -3
    -11.remainder(-4)            # => -3

    12.remainder(4)              # => 0
    12.remainder(-4)             # => 0
    -12.remainder(4)             # => 0
    -12.remainder(-4)            # => 0

    13.remainder(4.0)            # => 1.0
    13.remainder(Rational(4, 1)) # => (1/1)

    static VALUE
    int_remainder(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return num_remainder(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_remainder(x, y);
        }
        return Qnil;
    }

round(ndigits= 0, half: :up) → integer click to toggle source

Returns `self` rounded to the nearest value with a precision of `ndigits` decimal digits.

When `ndigits` is negative, the returned value has at least `ndigits.abs` trailing zeros:

    555.round(-1)      # => 560
    555.round(-2)      # => 600
    555.round(-3)      # => 1000
    -555.round(-2)     # => -600
    555.round(-4)      # => 0

Returns `self` when `ndigits` is zero or positive.

    555.round     # => 555
    555.round(1)  # => 555
    555.round(50) # => 555

If keyword argument `half` is given, and `self` is equidistant from the two candidate values, the rounding is according to the given `half` value:

- `:up` or `nil`: round away from zero:

      25.round(-1, half: :up)      # => 30
      (-25).round(-1, half: :up)   # => -30

- `:down`: round toward zero:

      25.round(-1, half: :down)    # => 20
      (-25).round(-1, half: :down) # => -20

- `:even`: round toward the candidate whose last nonzero digit is even:

      25.round(-1, half: :even)    # => 20
      15.round(-1, half: :even)    # => 20
      (-25).round(-1, half: :even) # => -20

Raises and exception if the value for `half` is invalid.

Related: `Integer#truncate`.

    static VALUE
    int_round(int argc, VALUE* argv, VALUE num)
    {
        int ndigits;
        int mode;
        VALUE nd, opt;

        if (!rb_scan_args(argc, argv, "01:", &nd, &opt)) return num;
        ndigits = NUM2INT(nd);
        mode = rb_num_get_rounding_option(opt);
        if (ndigits >= 0) {
            return num;
        }
        return rb_int_round(num, ndigits, mode);
    }

size → int click to toggle source

Document-method: `Integer#size`

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

    # File numeric.rb, line 199
    def size
      Primitive.attr! 'inline'
      Primitive.cexpr! 'rb_int_size(self)'
    end

succ → next_integer click to toggle source

Returns the successor integer of `self` (equivalent to `self + 1`):

    1.succ  #=> 2
    -1.succ #=> 0

`Integer#next` is an alias for `Integer#succ`.

Related: `Integer#pred` (predecessor value).

    VALUE
    rb_int_succ(VALUE num)
    {
        if (FIXNUM_P(num)) {
            long i = FIX2LONG(num) + 1;
            return LONG2NUM(i);
        }
        if (RB_BIGNUM_TYPE_P(num)) {
            return rb_big_plus(num, INT2FIX(1));
        }
        return num_funcall1(num, '+', INT2FIX(1));
    }

Also aliased as: next
times {|i| ... } → self click to toggle source
times → enumerator

Calls the given block `self` times with each integer in `(0..self-1)`:

    a = []
    5.times {|i| a.push(i) } # => 5
    a                        # => [0, 1, 2, 3, 4]

With no block given, returns an `Enumerator`.

    static VALUE
    int_dotimes(VALUE num)
    {
        RETURN_SIZED_ENUMERATOR(num, 0, 0, int_dotimes_size);

        if (FIXNUM_P(num)) {
            long i, end;

            end = FIX2LONG(num);
            for (i=0; i<end; i++) {
                rb_yield_1(LONG2FIX(i));
            }
        }
        else {
            VALUE i = INT2FIX(0);

            for (;;) {
                if (!RTEST(int_le(i, num))) break;
                rb_yield(i);
                i = rb_int_plus(i, INT2FIX(1));
            }
        }
        return num;
    }

to_bn() click to toggle source

Casts an `Integer` as an `OpenSSL::BN`

See ‘man bn` for more info.

    # File ext/openssl/lib/openssl/bn.rb, line 37
    def to_bn
      OpenSSL::BN::new(self)
    end

to_d → bigdecimal click to toggle source

Returns the value of `int` as a `BigDecimal`.

    require 'bigdecimal'
    require 'bigdecimal/util'

    42.to_d   # => 0.42e2

See also `BigDecimal::new`.

    # File ext/bigdecimal/lib/bigdecimal/util.rb, line 23
    def to_d
      BigDecimal(self)
    end

to_f → float click to toggle source

Converts `self` to a Float:

    1.to_f  # => 1.0
    -1.to_f # => -1.0

If the value of `self` does not fit in a Float, the result is infinity:

    (10**400).to_f  # => Infinity
    (-10**400).to_f # => -Infinity

    static VALUE
    int_to_f(VALUE num)
    {
        double val;

        if (FIXNUM_P(num)) {
            val = (double)FIX2LONG(num);
        }
        else if (RB_BIGNUM_TYPE_P(num)) {
            val = rb_big2dbl(num);
        }
        else {
            rb_raise(rb_eNotImpError, "Unknown subclass for to_f: %s", rb_obj_classname(num));
        }

        return DBL2NUM(val);
    }

to_i → integer click to toggle source

Since `int` is already an `Integer`, returns `self`.

`to_int` is an alias for `to_i`.

    # File numeric.rb, line 210
    def to_i
      return self
    end

to_int → integer click to toggle source

Since `int` is already an `Integer`, returns `self`.

    # File numeric.rb, line 218
    def to_int
      return self
    end

to_r → rational click to toggle source

Returns the value as a rational.

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

    static VALUE
    integer_to_r(VALUE self)
    {
        return rb_rational_new1(self);
    }

to_s(base = 10) → string click to toggle source

Returns a string containing the place-value representation of `self` in radix `base` (in 2..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"

Raises an exception if `base` is out of range.

`Integer#inspect` is an alias for `Integer#to_s`.

    MJIT_FUNC_EXPORTED VALUE
    rb_int_to_s(int argc, VALUE *argv, VALUE x)
    {
        int base;

        if (rb_check_arity(argc, 0, 1))
            base = NUM2INT(argv[0]);
        else
            base = 10;
        return rb_int2str(x, base);
    }

Also aliased as: inspect
truncate(ndigits = 0) → integer click to toggle source

Returns `self` truncated (toward zero) to a precision of `ndigits` decimal digits.

When `ndigits` is negative, the returned value has at least `ndigits.abs` trailing zeros:

    555.truncate(-1)  # => 550
    555.truncate(-2)  # => 500
    -555.truncate(-2) # => -500

Returns `self` when `ndigits` is zero or positive.

    555.truncate     # => 555
    555.truncate(50) # => 555

Related: `Integer#round`.

    static VALUE
    int_truncate(int argc, VALUE* argv, VALUE num)
    {
        int ndigits;

        if (!rb_check_arity(argc, 0, 1)) return num;
        ndigits = NUM2INT(argv[0]);
        if (ndigits >= 0) {
            return num;
        }
        return rb_int_truncate(num, ndigits);
    }

upto(limit) {|i| ... } → self click to toggle source
upto(limit) → enumerator

Calls the given block with each integer value from `self` up to `limit`; returns `self`:

    a = []
    5.upto(10) {|i| a << i }              # => 5
    a                                     # => [5, 6, 7, 8, 9, 10]
    a = []
    -5.upto(0) {|i| a << i }              # => -5
    a                                     # => [-5, -4, -3, -2, -1, 0]
    5.upto(4) {|i| fail 'Cannot happen' } # => 5

With no block given, returns an `Enumerator`.

    static VALUE
    int_upto(VALUE from, VALUE to)
    {
        RETURN_SIZED_ENUMERATOR(from, 1, &to, int_upto_size);
        if (FIXNUM_P(from) && FIXNUM_P(to)) {
            long i, end;

            end = FIX2LONG(to);
            for (i = FIX2LONG(from); i <= end; i++) {
                rb_yield(LONG2FIX(i));
            }
        }
        else {
            VALUE i = from, c;

            while (!(c = rb_funcall(i, '>', 1, to))) {
                rb_yield(i);
                i = rb_funcall(i, '+', 1, INT2FIX(1));
            }
            ensure_cmp(c, i, to);
        }
        return from;
    }

zero? → true or false click to toggle source

Returns `true` if `int` has a zero value.

    # File numeric.rb, line 226
    def zero?
      Primitive.attr! 'inline'
      Primitive.cexpr! 'rb_int_zero_p(self)'
    end

self | other → integer click to toggle source

Bitwise OR; each bit in the result is 1 if either corresponding bit in `self` or `other` is 1, 0 otherwise:

    "%04b" % (0b0101 | 0b0110) # => "0111"

Raises an exception if `other` is not an Integer.

Related: Integer#& (bitwise AND), Integer#^ (bitwise EXCLUSIVE OR).

    static VALUE
    int_or(VALUE x, VALUE y)
    {
        if (FIXNUM_P(x)) {
            return fix_or(x, y);
        }
        else if (RB_BIGNUM_TYPE_P(x)) {
            return rb_big_or(x, y);
        }
        return Qnil;
    }

~int → integer click to toggle source

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"

    # File numeric.rb, line 68
    def ~
      Primitive.attr! 'inline'
      Primitive.cexpr! 'rb_int_comp(self)'
    end