What does "wrong number of arguments (1 for 0)" mean in Ruby?

Question

What does "Argument Error: wrong number of arguments (1 for 0)" mean?

Answer 1

When you define a function, you also define what info (arguments) that function needs to work. If it is designed to work without any additional info, and you pass it some, you are going to get that error.

Example: Takes no arguments:

def dog end 

Takes arguments:

def cat(name) end 

When you call these, you need to call them with the arguments you defined.

dog                  #works fine cat("Fluffy")        #works fine   dog("Fido")          #Returns ArgumentError (1 for 0) cat                  #Returns ArgumentError (0 for 1) 

Check out the Ruby Koans to learn all this.

Answer 2

You passed an argument to a function which didn't take any. For example:

def takes_no_arguments end  takes_no_arguments 1 # ArgumentError: wrong number of arguments (1 for 0)