A Range represents an interval—a set of values with a start and an end. Ranges may be constructed using the s..e and s...e literals, or with Range::new. Ranges constructed using .. run from the start to the end inclusively. Those created using ... exclude the end value. When used as an iterator, ranges return each value in the sequence. 

   (-1..-5).to_a      #=> []
   (-5..-1).to_a      #=> [-5, -4, -3, -2, -1]
   ('a'..'e').to_a    #=> ["a", "b", "c", "d", "e"]
   ('a'...'e').to_a   #=> ["a", "b", "c", "d"]

Ranges can be constructed using objects of any type, as long as the objects can be compared using their <=> operator and they support the succ method to return the next object in sequence. 

   class Xs                # represent a string of 'x's
     include Comparable
     attr :length
     def initialize(n)
       @length = n
     end
     def succ
       Xs.new(@length + 1)
     end
     def <=>(other)
       @length <=> other.length
     end
     def to_s
       sprintf "%2d #{inspect}", @length
     end
     def inspect
       'x' * @length
     end
   end

   r = Xs.new(3)..Xs.new(6)   #=> xxx..xxxxxx
   r.to_a                     #=> [xxx, xxxx, xxxxx, xxxxxx]
   r.member?(Xs.new(5))       #=> true

In the previous code example, class Xs includes the Comparable module. This is because Enumerable#member? checks for equality using ==. Including Comparable ensures that the == method is defined in terms of the <=> method implemented in Xs.

Methods
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Included Modules
Class Public methods
Range.new(start, end, exclusive=false) => range

Constructs a range using the given start and end. If the third parameter is omitted or is false, the range will include the end object; otherwise, it will be excluded.

Source: show 

static VALUE
range_initialize(argc, argv, range)
    int argc;
    VALUE *argv;
    VALUE range;
{
    VALUE beg, end, flags;
    
    rb_scan_args(argc, argv, "21", &beg, &end, &flags);
    /* Ranges are immutable, so that they should be initialized only once. */
    if (rb_ivar_defined(range, id_beg)) {
        rb_name_error(rb_intern("initialize"), "`initialize' called twice");
    }
    range_init(range, beg, end, RTEST(flags));
    return Qnil;
}
yaml_new( klass, tag, val )

Source: show 

     # File lib/yaml/rubytypes.rb, line 201
201:     def Range.yaml_new( klass, tag, val )
202:         inr = %r'(\w+|[+-]?\d+(?:\.\d+)?(?:e[+-]\d+)?|"(?:[^\\"]|\\.)*")'
203:         opts = {}
204:         if String === val and val =~ /^#{inr}(\.{2,3})#{inr}$/o
205:             r1, rdots, r2 = $1, $2, $3
206:             opts = {
207:                 'begin' => YAML.load( "--- #{r1}" ),
208:                 'end' => YAML.load( "--- #{r2}" ),
209:                 'excl' => rdots.length == 3
210:             }
211:             val = {}
212:         elsif Hash === val
213:             opts['begin'] = val.delete('begin')
214:             opts['end'] = val.delete('end')
215:             opts['excl'] = val.delete('excl')
216:         end
217:         if Hash === opts
218:             r = YAML::object_maker( klass, {} )
219:             # Thank you, NaHi
220:             Range.instance_method(:initialize).
221:                   bind(r).
222:                   call( opts['begin'], opts['end'], opts['excl'] )
223:             val.each { |k,v| r.instance_variable_set( k, v ) }
224:             r
225:         else
226:             raise YAML::TypeError, "Invalid Range: " + val.inspect
227:         end
228:     end
Instance Public methods
rng == obj => true or false

Returns true only if obj is a Range, has equivalent beginning and end items (by comparing them with ==), and has the same exclude_end? setting as rng. 

  (0..2) == (0..2)            #=> true
  (0..2) == Range.new(0,2)    #=> true
  (0..2) == (0...2)           #=> false

Source: show 

static VALUE
range_eq(range, obj)
    VALUE range, obj;
{
    if (range == obj) return Qtrue;
    if (!rb_obj_is_instance_of(obj, rb_obj_class(range)))
        return Qfalse;

    if (!rb_equal(rb_ivar_get(range, id_beg), rb_ivar_get(obj, id_beg)))
        return Qfalse;
    if (!rb_equal(rb_ivar_get(range, id_end), rb_ivar_get(obj, id_end)))
        return Qfalse;

    if (EXCL(range) != EXCL(obj)) return Qfalse;

    return Qtrue;
}
rng === obj => true or false rng.member?(val) => true or false rng.include?(val) => true or false

Returns true if obj is an element of rng, false otherwise. Conveniently, === is the comparison operator used by case statements. 

   case 79
   when 1..50   then   print "low\n"
   when 51..75  then   print "medium\n"
   when 76..100 then   print "high\n"
   end

produces: 

   high

Source: show 

static VALUE
range_include(range, val)
    VALUE range, val;
{
    VALUE beg, end;

    beg = rb_ivar_get(range, id_beg);
    end = rb_ivar_get(range, id_end);
    if (r_le(beg, val)) {
        if (EXCL(range)) {
            if (r_lt(val, end)) return Qtrue;
        }
        else {
            if (r_le(val, end)) return Qtrue;
        }
    }
    return Qfalse;
}
rng.first => obj rng.begin => obj

Returns the first object in rng.

Source: show 

static VALUE
range_first(range)
    VALUE range;
{
    return rb_ivar_get(range, id_beg);
}
rng.each {| i | block } => rng

Iterates over the elements rng, passing each in turn to the block. You can only iterate if the start object of the range supports the succ method (which means that you can’t iterate over ranges of Float objects). 

   (10..15).each do |n|
      print n, ' '
   end

produces: 

   10 11 12 13 14 15

Source: show 

static VALUE
range_each(range)
    VALUE range;
{
    VALUE beg, end;

    RETURN_ENUMERATOR(range, 0, 0);

    beg = rb_ivar_get(range, id_beg);
    end = rb_ivar_get(range, id_end);

    if (!rb_respond_to(beg, id_succ)) {
        rb_raise(rb_eTypeError, "can't iterate from %s",
                 rb_obj_classname(beg));
    }
    if (FIXNUM_P(beg) && FIXNUM_P(end)) { /* fixnums are special */
        long lim = FIX2LONG(end);
        long i;

        if (!EXCL(range)) lim += 1;
        for (i=FIX2LONG(beg); i<lim; i++) {
            rb_yield(LONG2NUM(i));
        }
    }
    else if (TYPE(beg) == T_STRING) {
        VALUE args[5], iter[2];

        args[0] = beg; args[1] = end; args[2] = range;
        iter[0] = INT2FIX(1); iter[1] = INT2FIX(1);
        rb_iterate((VALUE(*)_((VALUE)))str_step, (VALUE)args, step_i,
                   (VALUE)iter);
    }
    else {
        range_each_func(range, each_i, beg, end, NULL);
    }
    return range;
}
rng.end => obj rng.last => obj

Returns the object that defines the end of rng. 

   (1..10).end    #=> 10
   (1...10).end   #=> 10

Source: show 

static VALUE
range_last(range)
    VALUE range;
{
    return rb_ivar_get(range, id_end);
}
rng.eql?(obj) => true or false

Returns true only if obj is a Range, has equivalent beginning and end items (by comparing them with eql?), and has the same exclude_end? setting as rng. 

  (0..2) == (0..2)            #=> true
  (0..2) == Range.new(0,2)    #=> true
  (0..2) == (0...2)           #=> false

Source: show 

static VALUE
range_eql(range, obj)
    VALUE range, obj;
{
    if (range == obj) return Qtrue;
    if (!rb_obj_is_instance_of(obj, rb_obj_class(range)))
        return Qfalse;

    if (!rb_eql(rb_ivar_get(range, id_beg), rb_ivar_get(obj, id_beg)))
        return Qfalse;
    if (!rb_eql(rb_ivar_get(range, id_end), rb_ivar_get(obj, id_end)))
        return Qfalse;

    if (EXCL(range) != EXCL(obj)) return Qfalse;

    return Qtrue;
}
rng.exclude_end? => true or false

Returns true if rng excludes its end value.

Source: show 

static VALUE
range_exclude_end_p(range)
    VALUE range;
{
    return EXCL(range) ? Qtrue : Qfalse;
}
rng.first => obj rng.begin => obj

Returns the first object in rng.

Source: show 

static VALUE
range_first(range)
    VALUE range;
{
    return rb_ivar_get(range, id_beg);
}
rng.hash => fixnum

Generate a hash value such that two ranges with the same start and end points, and the same value for the “exclude end” flag, generate the same hash value.

Source: show 

static VALUE
range_hash(range)
    VALUE range;
{
    long hash = EXCL(range);
    VALUE v;

    v = rb_hash(rb_ivar_get(range, id_beg));
    hash ^= v << 1;
    v = rb_hash(rb_ivar_get(range, id_end));
    hash ^= v << 9;
    hash ^= EXCL(range) << 24;

    return LONG2FIX(hash);
}
rng === obj => true or false rng.member?(val) => true or false rng.include?(val) => true or false

Returns true if obj is an element of rng, false otherwise. Conveniently, === is the comparison operator used by case statements. 

   case 79
   when 1..50   then   print "low\n"
   when 51..75  then   print "medium\n"
   when 76..100 then   print "high\n"
   end

produces: 

   high

Source: show 

static VALUE
range_include(range, val)
    VALUE range, val;
{
    VALUE beg, end;

    beg = rb_ivar_get(range, id_beg);
    end = rb_ivar_get(range, id_end);
    if (r_le(beg, val)) {
        if (EXCL(range)) {
            if (r_lt(val, end)) return Qtrue;
        }
        else {
            if (r_le(val, end)) return Qtrue;
        }
    }
    return Qfalse;
}
rng.inspect => string

Convert this range object to a printable form (using inspect to convert the start and end objects).

Source: show 

static VALUE
range_inspect(range)
    VALUE range;
{
    VALUE str, str2;

    str = rb_inspect(rb_ivar_get(range, id_beg));
    str2 = rb_inspect(rb_ivar_get(range, id_end));
    str = rb_str_dup(str);
    rb_str_cat(str, "...", EXCL(range)?3:2);
    rb_str_append(str, str2);
    OBJ_INFECT(str, str2);

    return str;
}
rng.end => obj rng.last => obj

Returns the object that defines the end of rng. 

   (1..10).end    #=> 10
   (1...10).end   #=> 10

Source: show 

static VALUE
range_last(range)
    VALUE range;
{
    return rb_ivar_get(range, id_end);
}
rng === obj => true or false rng.member?(val) => true or false rng.include?(val) => true or false

Returns true if obj is an element of rng, false otherwise. Conveniently, === is the comparison operator used by case statements. 

   case 79
   when 1..50   then   print "low\n"
   when 51..75  then   print "medium\n"
   when 76..100 then   print "high\n"
   end

produces: 

   high

Source: show 

static VALUE
range_include(range, val)
    VALUE range, val;
{
    VALUE beg, end;

    beg = rb_ivar_get(range, id_beg);
    end = rb_ivar_get(range, id_end);
    if (r_le(beg, val)) {
        if (EXCL(range)) {
            if (r_lt(val, end)) return Qtrue;
        }
        else {
            if (r_le(val, end)) return Qtrue;
        }
    }
    return Qfalse;
}
pretty_print(q)

Source: show 

     # File lib/pp.rb, line 351
351:   def pretty_print(q)
352:     q.pp self.begin
353:     q.breakable ''
354:     q.text(self.exclude_end? ? '...' : '..')
355:     q.breakable ''
356:     q.pp self.end
357:   end
rng.step(n=1) {| obj | block } => rng

Iterates over rng, passing each nth element to the block. If the range contains numbers, n is added for each iteration. Otherwise step invokes succ to iterate through range elements. The following code uses class Xs, which is defined in the class-level documentation. 

   range = Xs.new(1)..Xs.new(10)
   range.step(2) {|x| puts x}
   range.step(3) {|x| puts x}

produces: 

    1 x
    3 xxx
    5 xxxxx
    7 xxxxxxx
    9 xxxxxxxxx
    1 x
    4 xxxx
    7 xxxxxxx
   10 xxxxxxxxxx

Source: show 

static VALUE
range_step(argc, argv, range)
    int argc;
    VALUE *argv;
    VALUE range;
{
    VALUE b, e, step, tmp;

    RETURN_ENUMERATOR(range, argc, argv);

    b = rb_ivar_get(range, id_beg);
    e = rb_ivar_get(range, id_end);
    if (argc == 0) {
        step = INT2FIX(1);
    }
    else {
        rb_scan_args(argc, argv, "01", &step);
        if (!rb_obj_is_kind_of(step, rb_cNumeric)) {
            step = rb_to_int(step);
        }
        if (rb_funcall(step, '<', 1, INT2FIX(0))) {
            rb_raise(rb_eArgError, "step can't be negative");
        }
        else if (!rb_funcall(step, '>', 1, INT2FIX(0))) {
            rb_raise(rb_eArgError, "step can't be 0");
        }
    }

    if (FIXNUM_P(b) && FIXNUM_P(e) && FIXNUM_P(step)) { /* fixnums are special */
        long end = FIX2LONG(e);
        long i, unit = FIX2LONG(step);

        if (!EXCL(range))
            end += 1;
        i = FIX2LONG(b);       
        while (i < end) {
            rb_yield(LONG2NUM(i));
            if (i + unit < i) break;
            i += unit;
        }

    }
    else if (ruby_float_step(b, e, step, EXCL(range))) {
        /* done */
    }
    else if (rb_obj_is_kind_of(b, rb_cNumeric) ||
             !NIL_P(rb_check_to_integer(b, "to_int")) ||
             !NIL_P(rb_check_to_integer(e, "to_int"))) {
        ID op = EXCL(range) ? '<' : rb_intern("<=");

        while (RTEST(rb_funcall(b, op, 1, e))) {
            rb_yield(b);
            b = rb_funcall(b, '+', 1, step);
        }
    }
    else {
        tmp = rb_check_string_type(b);

        if (!NIL_P(tmp)) {
            VALUE args[5], iter[2];

            b = tmp;
            args[0] = e;
            args[1] = EXCL(range) ? Qtrue : Qfalse;
            iter[0] = INT2FIX(1);
            iter[1] = step;
            rb_block_call(b, rb_intern("upto"), 2, args, step_i, (VALUE)iter);
        }
        else if (rb_obj_is_kind_of(b, rb_cNumeric) ||
                 !NIL_P(rb_check_to_integer(b, "to_int")) ||
                 !NIL_P(rb_check_to_integer(e, "to_int"))) {
            ID c = EXCL(range) ? '<' : rb_intern("<=");

            while (RTEST(rb_funcall(b, c, 1, e))) {
                rb_yield(b);
                b = rb_funcall(b, '+', 1, step);
            }
        }
        else {
            VALUE args[2];

            if (!rb_respond_to(b, id_succ)) {
                rb_raise(rb_eTypeError, "can't iterate from %s",
                         rb_obj_classname(b));
            }
            args[0] = INT2FIX(1);
            args[1] = step;
            range_each_func(range, step_i, b, e, args);
        }
    }
    return range;
}
rng.to_s => string

Convert this range object to a printable form.

Source: show 

static VALUE
range_to_s(range)
    VALUE range;
{
    VALUE str, str2;

    str = rb_obj_as_string(rb_ivar_get(range, id_beg));
    str2 = rb_obj_as_string(rb_ivar_get(range, id_end));
    str = rb_str_dup(str);
    rb_str_cat(str, "...", EXCL(range)?3:2);
    rb_str_append(str, str2);
    OBJ_INFECT(str, str2);

    return str;
}
to_yaml( opts = {} )

Source: show 

     # File lib/yaml/rubytypes.rb, line 229
229:         def to_yaml( opts = {} )
230:                 YAML::quick_emit( self, opts ) do |out|
231:             # if self.begin.is_complex_yaml? or self.begin.respond_to? :to_str or
232:             #   self.end.is_complex_yaml? or self.end.respond_to? :to_str or
233:             #   not to_yaml_properties.empty?
234:                 out.map( taguri, to_yaml_style ) do |map|
235:                     map.add( 'begin', self.begin )
236:                     map.add( 'end', self.end )
237:                     map.add( 'excl', self.exclude_end? )
238:                     to_yaml_properties.each do |m|
239:                         map.add( m, instance_variable_get( m ) )
240:                     end
241:                 end
242:             # else
243:             #     out.scalar( taguri ) do |sc|
244:             #         sc.embed( self.begin )
245:             #         sc.concat( self.exclude_end? ? "..." : ".." )
246:             #         sc.embed( self.end )
247:             #     end
248:             # end
249:         end
250:         end