useful methods

methods:

show the methods of this object

ex:

10.methods

dup:

make a copy of original object

ex:

“test”.dup

reverse:

ex:

"test".reverse

--->"tset"

match:

ex:

match:

“test”.match(“es”)

not match:

“test”.match(“ed”)

is_a?:

decide if the object is this type

ex:

"test".is_a?(String)

---> true

ancestors:

ex:

Integer.ancestors

-- [Integer, Precision, Numeric, Comparable, Object, Kernel]

inspect

return the string representation of object

ex:

[1,2,3].inspect

--> "[1,2,3]"

note:  p  [1,2,3]  equals [1,2,3].inspect

superclass:

class method, tell the superclass of  class