Ruby新手求助：如何解决ArgumentError（参数数量不匹配）问题

错误原因 #

报错信息wrong number of arguments (given 0, expected 2)的核心问题：你在条件判断代码中直接写了ideal_weight，Ruby会将其视为调用ideal_weight方法但未传入任何参数，但该方法定义时要求必须传入height和gender两个参数，因此触发了参数数量不匹配的异常。

修复步骤 #

1. 保存方法调用的返回值
   调用ideal_weight(height, gender)时，把计算结果存入一个变量，避免后续误将方法名当作变量使用：

calculated_ideal_weight = ideal_weight(height, gender)

2. 简化方法的返回逻辑（可选但更严谨）
   Ruby默认会返回方法最后一行的执行结果，因此可以去掉方法内的变量赋值，直接返回计算式；同时增加未知性别的处理分支，避免返回nil引发后续错误：

def ideal_weight(height, gender) # Ideal weight calculation
   if gender == "E" 
      (height - 100) - (height - 150) / 4
   elsif gender == "K"
      (height - 100) - (height - 150) / 2
   else
      nil # 处理未知性别情况
   end
end

3. 修改条件判断的变量引用
   将所有判断中的ideal_weight替换为刚才保存结果的变量，并增加未知性别的提示：

if calculated_ideal_weight.nil?
    puts "Invalid gender input. Please use 'E' or 'K'."
elsif calculated_ideal_weight < weight
    puts "obese"
elsif calculated_ideal_weight == weight
    puts "ideal"
else
    puts "light"
end

修复后的完整代码 #

def ideal_weight(height, gender) # Ideal weight calculation
   if gender == "E" 
      (height - 100) - (height - 150) / 4
   elsif gender == "K"
      (height - 100) - (height - 150) / 2
   else
      nil
   end
end 

puts "Please enter your height, weight and gender..."
height, weight, gender = gets.chomp.split
height = height.to_i
weight = weight.to_i
calculated_ideal_weight = ideal_weight(height, gender)

if calculated_ideal_weight.nil?
    puts "Invalid gender input. Please use 'E' or 'K'."
elsif calculated_ideal_weight < weight
    puts "obese"
elsif calculated_ideal_weight == weight
    puts "ideal"
else
    puts "light"
end

内容的提问来源于stack exchange，提问作者ahailtotheKing