如何检查Ruby哈希是否包含gets.chomp获取的单词及代码问题解决

Let's break down the issues in your code and fix them step by step to properly check if the hash already has the word the user inputs:

First, let's list the problems in your original code: #

• Redundant condition: You're checking action == "1" again inside the if action == "1" block—this is totally unnecessary.
• Error-prone nil check: When the word isn't in the hash, words[word] returns nil, and calling empty? on nil will throw a NoMethodError (since nil doesn't have an empty? method).
• Broken string interpolation: {Word} won't get replaced with the actual word—Ruby uses #{variable} for string interpolation.
• No feedback for existing words: If the user inputs a word that's already been added, your code does nothing, which is confusing for the user.
• Unstoppable loop: There's no way to exit the program without force-quitting it.

Here's the fixed code: #

words = {}
while true
  puts "What do you want to do?"
  puts "1) Teach a word to Baby."
  puts "2) Check how many words Baby has learned."
  puts "3) Exit"
  action = gets.chomp

  case action
  when "1"
    puts "Write a word that you want to teach Baby:"
    word = gets.chomp.capitalize

    # Correct way to check if the hash DOESN'T have the word
    if !words.key?(word)
      words[word] = Time.now
      puts "Success! You taught #{word} to Baby."
    else
      puts "Baby already knows the word #{word}!"
    end
  when "2"
    puts "Baby has learned #{words.size} words so far."
  when "3"
    puts "Goodbye!"
    break
  else
    puts "Invalid option—please enter 1, 2, or 3."
  end
end

Key fixes explained: #

• Checking for existing keys: words.key?(word) is the cleanest, most readable way to check if a hash contains a specific key. Alternatively, you could use words.has_key?(word) (it's an alias) or words[word].nil? (since accessing a non-existent key in a Ruby hash returns nil).
• Proper string interpolation: #{word} replaces the placeholder with the actual user-input word.
• Handled all cases: Added feedback for duplicate words, a way to exit the program, and error handling for invalid actions.
• Used a case statement: Makes handling multiple actions cleaner than nested if statements.

内容的提问来源于stack exchange，提问作者Dion