0

这是我下面代码的一部分，无论如何，这是唯一不起作用的东西。我很困惑。

def change_numbers_to_grade_points
 @course_grades.each do |grade|
   case
   when grade < 100 && grade > 93.99
     grade == 4.0

   when grade < 93.99 && grade > 89.99
     grade == 3.7

   when grade < 88.99 && grade > 86.99
     grade == 3.3

   when grade < 86.99 && grade > 82.99
     grade == 3.0

   when grade < 82.99 && grade > 79.99
     grade == 2.7

   when grade < 79.99 && grade > 76.99
     grade == 2.3

   when grade < 76.99 && grade > 72.99
     grade == 2.0

   when grade < 72.99 && grade > 69.99
     grade == 1.7

   when grade < 69.99 && grade > 66.99
     grade == 1.3

   when grade < 66.99 && grade > 59.99
     grade == 1.0

   when grade < 59.99 && grade > 0
     grade == 0.0
   else
     puts "Something went wrong with conversion!"
     puts
   end
 end
end
4

2 回答 2

2

==是平等。您想=用于分配。

例如：

when grade < 100 && grade > 93.99
  grade = 4.0

但是，这也不是问题，因为您没有修改使用循环迭代的数组中的任何.each元素

考虑类似的东西

@course_grades.size.times do |i|
   grade = @course_grades[i]
   if # something
      @course_grades[i] = #some new value
   end
end
于 2013-11-14T04:22:58.353 回答
0

正如其他用户所建议的那样，您应该真正使用map!，因为您想使用case. 顺便说一句，lambdas您可以使用Ranges. 如下：

 # Since your method is changing the contents of
 # an instance variable, the convention is that
 # your method ends with a bang (!)
 def change_numbers_to_grade_points!
    @course_grades.map! do |grade|
     case grade
     when 93.99..100
       4.0

     when 89.99..93.99
       3.7

     when 86.99..88.99
       3.3

     when 82.99..86.99
       3.0

     #...

     #An error is raised if something is wrong because of map!
      else
        raise "Something went wrong"
      end
    end
于 2013-11-14T05:28:45.213 回答