Python 为什么我的if语句在此分级代码中不起作用？

这是我的代码，我想让它通过并选择它适合的类别，但它总是给我F

import random

def rand(start, stop):
  print random.randint(start,stop)

def grader(rand):
  print "Your test score is "
  x = rand(50, 100)
  if x >= 90:
    print "which is an A."
  elif x <= 89 and x >= 80:
    print "which is a B."
  elif x <= 79 and x >= 70:
    print "which is a C."
  elif x <= 69 and x >=60:
    print "which is a D."
  else:
    print "which is a F."

随机导入
def rand（启动、停止）：
打印random.randint（开始、停止）
def分级器（兰德）：
打印“您的考试成绩为”
x=兰特（50100）
如果x>=90：
打印“哪个是A。”
elif x=80：
打印“哪个是B”
elif x=70：
打印“哪个是C”
elif x=60：
打印“哪个是D”
其他：
打印“哪个是F”

您的

rand

函数正在返回

None

，因为它正在打印值，而不是返回值。此外，好的做法是将其命名为更具描述性的名称，例如

get\u random

或

get\u random\u number

。另外，您的

get_random

函数做的事情与

randint

做的事情完全相同，但我会告诉您一些疑问（需要添加更多功能？）

作为奖励，我加入了一个例子，说明鲜为人知的

对分
库是如何完美地解决这类值相交问题的

示例：

import bisect, random

def get_random(start, stop):
  return random.randint(start,stop)

def match_grade(score):
    breakpoints = [60, 70, 80, 90]
    grades = ["which is a F.", "which is a D.", 
    "which is a C.", "which is a B.", "which is an A."]
    bisect_index = bisect.bisect(breakpoints, score)
    return grades[bisect_index]

random_number = get_random(50, 100)
grade_range = match_grade(random_number)
print "Your test score is {}, {}".format(random_number, grade_range)

Your test score is 63, which is a D.

样本输出：

import bisect, random

def get_random(start, stop):
  return random.randint(start,stop)

def match_grade(score):
    breakpoints = [60, 70, 80, 90]
    grades = ["which is a F.", "which is a D.", 
    "which is a C.", "which is a B.", "which is an A."]
    bisect_index = bisect.bisect(breakpoints, score)
    return grades[bisect_index]

random_number = get_random(50, 100)
grade_range = match_grade(random_number)
print "Your test score is {}, {}".format(random_number, grade_range)

Your test score is 63, which is a D.

print
不是
return
。为什么您需要自己的函数来执行与
random.randint（）完全相同的操作？
？我的老师让我把它放在：/，