ascii轉字元或者字串轉ascii
"a".ord # => 97 "!".ord # => 33 "\n".ord # => 10
'a'[0] # => "a" 'bad sound'[1] # => "a" 'a'[0].ord # => 97 'bad sound'[1].ord # => 97
97.chr # => "a"
符號轉字串
:a_symbol.to_s # => "a_symbol" :AnotherSymbol.id2name # => "AnotherSymbol" :"Yet another symbol!".to_s # => "Yet another symbol!"
通過字串得到相應的符號
:dodecahedron.object_id # => 516488 symbol_name = "dodecahedron" symbol_name.intern # => :dodecahedron symbol_name.intern.object_id # => 516488
符號由一個名字和一個internal id 組成，相同符號引用同一個物件，但是兩個內容一樣的字串卻是不同的物件
"string".object_id # =>70309575257960 "string".object_id # =>70309575257221 :symbol.object_id # => 87690 :symbol.object_id # => 87690
如果物件內容重要使用字串，如果物件唯一性重要使用符號