.class 运行时类型识别

#  E5.3-2.rb   
a=5
print "a = ",a,"    ", a.class, "\n"

a="hh"   # a: 5 --> "hh"
print "a = ",a,"    ", a.class, "\n"

=begin
a = 5    Fixnum
a = hh    String
=end