[RUBY] What you learned about symbols

Precautions for creating symbols

`How to write with an error`


#Error occurs if you use an invalid string as an identifier (starting with a number, including hyphens, spaces)
:5678             #=>SyntaxError
:rails-is-easy    #=>Nameerror
:rails is easy    #=>SyntaxError
:()               #=>SyntaxError

#Effective as a symbol when surrounded by a single quote
:'5678'           #=>"5678"
:'rails-is-easy'  #=>"rails-is-easy"
:'rails is easy'  #=>"rails is easy"
:'()'             #=>"()"

`Expression expansion in a symbol`


#Use double quotes
title = 'Taro'
:"#{title.upcase}" #=> :TARO

Symbols and strings

Strings and symbols are different, so they are not compatible. However, there are methods that convert strings to symbols and methods that convert symbols to strings.

`python`


string = 'ruby'
sypbol = :ruby
string == symbol #=> false

#to_sym method:Convert strings to symbols
string.to_sym           #=> :ruby 
string.to_sym == symbol #=> true

#to_s method:Convert symbols to strings
symbol.to_s           #=> "ruby" 
symbol.to_s == string #=> true

References An introduction to Ruby for those who want to become professionals