为什么我的if语句在这个分级代码中不起作用？

Question

这是我的代码，我想它要经过，并选择它适合于哪一类，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." 

Answer 1

，而不是返回random.randint(start,stop)的，你打印。

变化

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

到

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

Answer 2

你rand函数返回None，因为它是印刷的，而不是返回一个值。另外，最好的做法是将其命名为更具描述性的内容，如get_random或get_random_number。另外，您的get_random功能确实与randint的功能完全相同，但我会给您带来疑问的好处（需要添加更多功能？）。

作为奖励，我已经包含了一个例子，知道如何知道bisect库对于这些类型的价值交叉点问题是完美的！

实施例：

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) 

样本输出：

Your test score is 63, which is a D.