ruby: undefined method exclude?

Question

I try to use the opposite method of include? in ruby, which is "string|array.exclude?", here's my code on interactive ruby.

this = "nice"
puts this.exclude? "n"

However, it always declares an error.

Traceback (most recent call last):

    4: from C:/Ruby26-x64/bin/irb.cmd:31:in `<main>'
    3: from C:/Ruby26-x64/bin/irb.cmd:31:in `load'
    2: from C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/irb-1.0.0/exe/irb:11:in `<top (required)>'
    1: from (irb):14

NoMethodError (undefined method `exclude?' for "nice":String)

I researched a lot but didn't find a solution. I wonder if it only happens to me, it annoys me so much.

Could someone help me out. Thank you very much.

Answer 1

String#exclude? is a part of activesupport gem that gets installed with every rails project. It is not included into ruby's standard library. But this method is quite simple:

def exclude?(string)
  !include?(string)
end