The Book of Ruby

Characters and Compatibility

The open_close.rb program is written for Ruby 1.9 and cannot be run in Ruby 1.8. This is because when a single character is returned by Ruby 1.8, it is treated as an integer ASCII value, whereas in Ruby 1.9 it is treated as a one-character string. So, when getc() returns the character, c, Ruby 1.8 is able to test its ASCII value ( c == 10 ), whereas Ruby 1.9 must either test it as a string ( c == "\n" ) or convert the character to an integer using the ord method: ( c.ord == 10 ). The ord method does not exist in Ruby 1.8.

As a general principle, if you want to write programs that work in different versions of Ruby, you may code around incompatibility issues by testing the value of the RUBY_VERSION constant. This constant ...