Ruby Difference for p & puts & print

they are all used to printout info, but they are different.

p is using the .inspect method, however, puts is using .to_s method.

Proof

example codes:

class Foo
    def inspect
        "In Foo inspect"
    end

    def to_s
        "In Foo to_s"
    end
end

foo = Foo.new

p foo
puts foo

outputs:

In Foo inspect
In Foo to_s

main difference

puts always try to convert to string

p print raw inputs, more useful and powerful in debugging

pretty-print

grateful to this answer on stackoverflow: @gioele

p is used to inspect a variable as a debug aide. It works printing the output of the method #inspect. For example p foo will output the content of foo.inspect.

Sometimes you need to debug complex variables or nested variables. In this case p will output a long line that is hard to understand. Instead, pp will put try to arrange the content of the variable so that it is easier to understand, for example indenting nested arrays or using one line for each instance variable of a complex object. pp does this calling the #pretty_inspect method (the pp library adds #pretty_inspect methods to many classes such as String, Array or Struct).

To remember: p = print, pp = pretty print.

Summary