class Integer

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);
    }
}

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.

static VALUE
int_s_try_convert(VALUE self, VALUE num)
{
    return rb_check_integer_type(num);
}

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)

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);
}

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;
}

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, '*');
}

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;
}

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, '+');
}

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, '-');
}

Returns self, negated.

# File numeric.rb, line 80
def -@
  Primitive.attr! :leaf
  Primitive.cexpr! 'rb_int_uminus(self)'
end

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;
}

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;
}

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;
}

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;
}

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));
    }
}

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;
}

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;
}

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#<<.

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;
}

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;
}

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;
}

Returns the absolute value of self.

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

# File numeric.rb, line 113
def abs
  Primitive.attr! :leaf
  Primitive.cexpr! 'rb_int_abs(self)'
end

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);
}

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 RBOOL(!int_zero_p(rb_int_and(num, mask)));
}

Returns the number of bits of the value of self, which is the bit position of the highest-order bit that 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), returns zero.

This method returns ceil(log2(self < 0 ? -self : self + 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

For Integer n, this method can be used to detect overflow in Array#pack:

if n.bit_length < 32
  [n].pack('l') # No overflow.
else
  raise 'Overflow'
end

# File numeric.rb, line 160
def bit_length
  Primitive.attr! :leaf
  Primitive.cexpr! 'rb_int_bit_length(self)'
end

Returns an integer that is a “ceiling” value for self, as specified by the given ndigits, which must be an integer-convertible object.

• When self is zero, returns zero (regardless of the value of ndigits):

  0.ceil(2)  # => 0
  0.ceil(-2) # => 0
  

• When self is non-zero and ndigits is non-negative, returns self:

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

• When self is non-zero and ndigits is negative, returns a value based on a computed granularity:

  • The granularity is 10 ** ndigits.abs.

  • The returned value is the smallest multiple of the granularity that is greater than or equal to self.

  Examples with positive self:

  ndigits	Granularity	1234.ceil(ndigits)
  -1	10	1240
  -2	100	1300
  -3	1000	2000
  -4	10000	10000
  -5	100000	100000

  Examples with negative self:

  ndigits	Granularity	-1234.ceil(ndigits)
  -1	10	-1230
  -2	100	-1200
  -3	1000	-1000
  -4	10000	0
  -5	100000	0

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);
}

Returns the result of division self by numeric. rounded up to the nearest integer.

3.ceildiv(3)   # => 1
4.ceildiv(3)   # => 2

4.ceildiv(-3)  # => -1
-4.ceildiv(3)  # => -1
-4.ceildiv(-3) # => 2

3.ceildiv(1.2) # => 3

# File numeric.rb, line 284
def ceildiv(other)
  -div(0 - other)
end

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);
}

Returns an array with both a numeric and a int represented as Integer objects or Float objects.

This is achieved by converting numeric to an Integer or a Float.

A TypeError is raised if the numeric is not an Integer or a Float 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);
    }
}

Returns 1.

# File numeric.rb, line 302
def denominator
  1
end

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;
}

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);
}

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;
}

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;
}

Returns true if self is an even number, false otherwise.

# File numeric.rb, line 169
def even?
  Primitive.attr! :leaf
  Primitive.cexpr! 'rb_int_even_p(self)'
end

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;
}

Returns an integer that is a “floor” value for self, as specified by the given ndigits, which must be an integer-convertible object.

• When self is zero, returns zero (regardless of the value of ndigits):

  0.floor(2)  # => 0
  0.floor(-2) # => 0
  

• When self is non-zero and ndigits is non-negative, returns self:

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

• When self is non-zero and ndigits is negative, returns a value based on a computed granularity:

  • The granularity is 10 ** ndigits.abs.

  • The returned value is the largest multiple of the granularity that is less than or equal to self.

  Examples with positive self:

  ndigits	Granularity	1234.floor(ndigits)
  -1	10	1230
  -2	100	1200
  -3	1000	1000
  -4	10000	0
  -5	100000	0

  Examples with negative self:

  ndigits	Granularity	-1234.floor(ndigits)
  -1	10	-1240
  -2	100	-1300
  -3	1000	-2000
  -4	10000	-10000
  -5	100000	-100000

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);
}

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);
}

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));
}

Since self is already an Integer, always returns true.

# File numeric.rb, line 178
def integer?
  true
end

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);
}

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 RBOOL(int_zero_p(rb_int_and(num, mask)));
}

Returns self.

# File numeric.rb, line 294
def numerator
  self
end

Returns true if self is an odd number, false otherwise.

# File numeric.rb, line 188
def odd?
  Primitive.attr! :leaf
  Primitive.cexpr! 'rb_int_odd_p(self)'
end

Returns self; intended for compatibility to character literals in Ruby 1.9.

# File numeric.rb, line 198
def ord
  self
end

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);
}

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));
}

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);
}

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)) {
        if (FIXNUM_P(y)) {
            VALUE z = fix_mod(x, y);
            RUBY_ASSERT(FIXNUM_P(z));
            if (z != INT2FIX(0) && (SIGNED_VALUE)(x ^ y) < 0)
                z = fix_minus(z, y);
            return z;
        }
        else if (!RB_BIGNUM_TYPE_P(y)) {
            return num_remainder(x, y);
        }
        x = rb_int2big(FIX2LONG(x));
    }
    else if (!RB_BIGNUM_TYPE_P(x)) {
        return Qnil;
    }
    return rb_big_remainder(x, y);
}

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);
}

Returns the number of bytes in the machine representation of self; the value is system-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 215
def size
  Primitive.attr! :leaf
  Primitive.cexpr! 'rb_int_size(self)'
end

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

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

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));
}

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.

# File numeric.rb, line 231
def times
  Primitive.attr! :inline_block
  unless defined?(yield)
    return Primitive.cexpr! 'SIZED_ENUMERATOR(self, 0, 0, int_dotimes_size)'
  end
  i = 0
  while i < self
    yield i
    i = i.succ
  end
  self
end

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

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);
}

Returns self (which is already an Integer).

# File numeric.rb, line 248
def to_i
  self
end

Returns self (which is already an Integer).

# File numeric.rb, line 256
def to_int
  self
end

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);
}

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.

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);
}

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);
}

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;
}

Returns true if self has a zero value, false otherwise.

# File numeric.rb, line 264
def zero?
  Primitive.attr! :leaf
  Primitive.cexpr! 'rb_int_zero_p(self)'
end

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;
}

One’s complement: returns the value of self with each bit inverted.

Because an integer value is 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 99
def ~
  Primitive.attr! :leaf
  Primitive.cexpr! 'rb_int_comp(self)'
end