class Integer - Ruby 2.2.4 Core API Reference API Reference

Ruby 2.2 Core API

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class Integer

This class is the basis for the two concrete classes that hold whole numbers, Bignum and Fixnum.

In Files

numeric.c
rational.c

Parent

Numeric

Public Instance Methods

to_i → integer click to toggle source

As int is already an Integer, all these methods simply return the receiver.

Synonyms are to_int, floor, ceil, truncate.

static VALUE
int_to_i(VALUE num)
{
    return num;
}

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

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

65.chr    #=> "A"
230.chr   #=> "\346"
255.chr(Encoding::UTF_8)   #=> "\303\277"

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, "%d 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_check_arity(argc, 0, 1);
        break;
    }
    enc = rb_to_encoding(argv[0]);
    if (!enc) enc = rb_ascii8bit_encoding();
  decode:
    return rb_enc_uint_chr(i, enc);
}

denominator → 1 click to toggle source

Returns 1.

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

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

downto(limit) → an_enumerator

Iterates the given block, passing 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, ".. " }
print "  Liftoff!\n"
#=> "5.. 4.. 3.. 2.. 1..   Liftoff!"

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.

static VALUE
int_even_p(VALUE num)
{
    if (rb_funcall(num, '%', 1, INT2FIX(2)) == INT2FIX(0)) {
        return Qtrue;
    }
    return Qfalse;
}

to_i → integer click to toggle source

As int is already an Integer, all these methods simply return the receiver.

Synonyms are to_int, floor, ceil, truncate.

static VALUE
int_to_i(VALUE num)
{
    return num;
}

gcd(int2) → integer click to toggle source

Returns the greatest common divisor (always positive). 0.gcd(x) and x.gcd(0) return abs(x).

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(int2) → array click to toggle source

Returns an array; [int.gcd(int2), int.lcm(int2)].

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));
}

integer? → true click to toggle source

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

static VALUE
int_int_p(VALUE num)
{
    return Qtrue;
}

lcm(int2) → integer click to toggle source

Returns the least common multiple (always positive). 0.lcm(x) and x.lcm(0) return zero.

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);
}

next → integer click to toggle source

succ → integer

Returns the Integer equal to int + 1, same as #next.

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

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

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.

static VALUE
int_odd_p(VALUE num)
{
    if (rb_funcall(num, '%', 1, INT2FIX(2)) != INT2FIX(0)) {
        return Qtrue;
    }
    return Qfalse;
}

ord → self click to toggle source

Returns the int itself.

a.ord    #=> 97

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

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

static VALUE
int_ord(VALUE num)
{
    return num;
}

pred → integer click to toggle source

Returns the Integer equal to int - 1.

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

VALUE
rb_int_pred(VALUE num)
{
    if (FIXNUM_P(num)) {
        long i = FIX2LONG(num) - 1;
        return LONG2NUM(i);
    }
    if (RB_TYPE_P(num, T_BIGNUM)) {
        return rb_big_minus(num, INT2FIX(1));
    }
    return rb_funcall(num, '-', 1, 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_scan_args(argc, argv, "01", NULL);
    return integer_to_r(self);
}

round([ndigits]) → integer or float click to toggle source

Rounds int to a given precision in decimal digits (default 0 digits).

Precision may be negative. Returns a floating point number when ndigits is positive, self for zero, and round down for negative.

1.round        #=> 1
1.round(2)     #=> 1.0
15.round(-1)   #=> 20

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

    if (argc == 0) return num;
    rb_scan_args(argc, argv, "1", &n);
    ndigits = NUM2INT(n);
    if (ndigits > 0) {
        return rb_Float(num);
    }
    if (ndigits == 0) {
        return num;
    }
    return int_round_0(num, ndigits);
}

next → integer click to toggle source

succ → integer

Returns the Integer equal to int + 1, same as #next.

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

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

times {|i| block } → self click to toggle source

times → an_enumerator

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 do |i|
  print i, " "
end
#=> 0 1 2 3 4

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(LONG2FIX(i));
        }
    }
    else {
        VALUE i = INT2FIX(0);

        for (;;) {
            if (!RTEST(rb_funcall(i, '<', 1, num))) break;
            rb_yield(i);
            i = rb_funcall(i, '+', 1, INT2FIX(1));
        }
    }
    return num;
}

to_i → integer click to toggle source

As int is already an Integer, all these methods simply return the receiver.

Synonyms are to_int, floor, ceil, truncate.

static VALUE
int_to_i(VALUE num)
{
    return num;
}

to_i → integer click to toggle source

As int is already an Integer, all these methods simply return the receiver.

Synonyms are to_int, floor, ceil, truncate.

static VALUE
int_to_i(VALUE num)
{
    return num;
}

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_i → integer click to toggle source

As int is already an Integer, all these methods simply return the receiver.

Synonyms are to_int, floor, ceil, truncate.

static VALUE
int_to_i(VALUE num)
{
    return num;
}

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

upto(limit) → an_enumerator

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.

For example:

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

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));
        }
        if (NIL_P(c)) rb_cmperr(i, to);
    }
    return from;
}

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