Question

将其简化为帖子（大多数“”是我的程序中完全正常运行的实际代码）：

studentName = ""

def getExamPoints (total):

"calculates examPoints here"

def getHomeworkPoints (total):
"calculates hwPoints here"

def getProjectPoints (total):
"calculates projectPoints here"

def computeGrade ():
if studentScore>=90:
     grade='A'
elif studentScore>=80:
        grade='B'
elif studentScore>=70:
        grade='C'
elif studentScore>=60:
        grade='D'
else:
    grade='F'


def main():

classAverage = 0.0      # All below is pre-given/ required code
classAvgGrade = "C"

studentScore = 0.0
classTotal = 0.0
studentCount = 0
gradeReport = "\n\nStudent\tScore\tGrade\n============================\n"

studentName = raw_input ("Enter the next student's name, 'quit' when done: ")

while studentName != "quit":

    studentCount = studentCount + 1

    examPoints = getExamPoints (studentName)
    hwPoints = getHomeworkPoints (studentName)
    projectPoints = getProjectPoints  (studentName)

    studentScore = examPoints + hwPoints + projectPoints #(<---- heres where my problem is!)

    studentGrade = computeGrade (studentScore)


main()

继续说：

文件“/home/hilld5/DenicaHillPP4.py”，第65行，在main中       studentScore = examPoints + hwPoints + projectPoints

TypeError：+不支持的操作数类型：'NoneType'和   'NoneType'

我从来没有学过或听说过非类型错误，即使用谷歌搜索它也没有真正理解。有谁认为他们了解发生了什么/知道什么是非类型？

Answer 1

这就是Python的方式，即值为None（NoneType是“值None的类型”）。

他们None的原因是因为你的函数实际上并没有return一个值，所以分配调用函数的结果只会赋予None。

举个例子：

>>> def foo():
...   x = 1
...
>>> print foo()
None
>>> def bar():
...   x = 1
...   return x
...
>>> print bar()
1

Answer 2

NoneType是None的类型。就那么简单。这意味着你正在做这样的事情：

a = b = None
c = a + b

什么是非类型？真的不明白

2 个答案: