[英]undefined method (NoMethodError) ruby
我一直收到以下錯誤消息:
text.rb:2:in `<main>': undefined method `choices' for main:Object (NoMethodError)
但我似乎無法理解為什么我的方法是“未定義的”:
puts "Select [1] [2] [3] or [q] to quit"; users_choice = gets.chomp
choices(users_choice)
def choices (choice)
while choice != 'q'
case choice
when '1'
puts "you chose one!"
when '2'
puts "you chose two!"
when '3'
puts "you chose three!"
end
end
end
這是因為在定義方法之前,您正在調用方法choices
。 編寫如下代碼:
puts "Select [1] [2] [3] or [q] to quit"
users_choice = gets.chomp
def choices (choice)
while choice != 'q'
case choice
when '1'
break puts "you chose one!"
when '2'
break puts "you chose two!"
when '3'
break puts "you chose three!"
end
end
end
choices(users_choice)
我用break
來退出while
循環。 否則它將創建一個無限循環。
def main
puts "Select [1] [2] [3] or [q] to quit"; users_choice = gets.chomp
choices(users_choice)
end
def choices (choice)
while choice != 'q'
case choice
when '1'
puts "you chose one!"
break
when '2'
puts "you chose two!"
break
when '3'
puts "you chose three!"
break
end
end
end
main
該方法只需在執行之前調用。 這里我在main方法中包裝了定義,但是在choice()的定義之后只調用main。
我在Eclipse中運行Ruby時遇到了同樣的錯誤,正在進行App Academy練習練習。 我忘了添加“對象”。 提供的測試用例。 以下語法有效:
#!/usr/bin/ruby
class Prime
# Write a method that takes in an integer (greater than one) and
# returns true if it is prime; otherwise return false.
#
# You may want to use the `%` modulo operation. `5 % 2` returns the
# remainder when dividing 5 by 2; therefore, `5 % 2 == 1`. In the case
# of `6 % 2`, since 2 evenly divides 6 with no remainder, `6 % 2 == 0`.
# More generally, if `m` and `n` are integers, `m % n == 0` if and only
# if `n` divides `m` evenly.
#
# You would not be expected to already know about modulo for the
# challenge.
#
# Difficulty: medium.
def primer(number)
if number < 2
return false
end
i = 10
while i > 1
if number > i && number != i
if number % i == 0
return false
end
end
i -= 1
end
return true
end
end
object = Prime. new
# These are tests to check that your code is working. After writing
# your solution, they should all print true.
puts("\nTests for #primer")
puts("===============================================")
puts('primer(2) == true: ' + (object.primer(2) == true).to_s)
puts('primer(3) == true: ' + (object.primer(3) == true).to_s)
puts('primer(4) == false: ' + (object.primer(4) == false).to_s)
puts('primer(9) == false: ' + (object.primer(9) == false).to_s)
puts("===============================================")
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