What is the purpose of “!” and “?” at the end of method names?

Question

Sometimes I see methods in Ruby that have \"?\" and \"!\" at the end of them, e.g:

name = \"sample_string\"
name.reverse
name.reverse!
name.is_binary_data?
<         


        

Answer 1

In contrast to the – I suppose – majority of programming languages ...

Ruby, methods are allowed to end with question marks or exclamation marks.

By convention, methods that answer questions (i.e. Array#empty? returns true if the receiver is empty) end in question marks.

Potentially “dangerous” methods (ie methods that modify self or the arguments, exit! etc.) by convention end with exclamation marks.

From: http://www.ruby-lang.org/en/documentation/ruby-from-other-languages/, Section Funny method names