Ruby On Rails 面试题与答案

Question: What is the convention using �!� at the end of method name?

The ! indicates that the method is about to change the object itself.

Here�s an example:

foo = "A TEST STRING"  # a string called foo

foo.downcase!     # modifies foo permanently
a test string

puts foo          # prints modified foo
a test string

Similarly if you did not want the object to be changed you could have something simple like:

foo2 = "A 2nd Test String"  # a string called foo 

foo2.downcase     # modifies foo temporarily
a 2nd test string 

puts foo2 nbsp;    # prints original foo 
A 2nd Test String