在这种情况下，我对python和任何语言都很陌生。一周前我开始学习。我正在尝试创建这个程序，只需将你的字母成绩计算出来就可以为你计算GPA。直到我收到错误的结尾都是顺利的。我会告诉你错误
这是代码，错误信息将显示在底部。
$def grades(grades_combined):
print "This program will tell you what your total GPA for the semester is."
print "Just enter your grades, and Voila!"
a_1 = 4.4
a = 4.0
a_2 = 3.6
b_1 = 3.4
b = 3.0
b_2 = 2.6
c_1 = 2.4
c = 2
c_2 = 1.6
d_1 = 1.4
d = 1
d_2 = 0.6
f = 0
print """We are going to ask you for all letter grades, in any order. Please
put the letter first, and then the symbol (if any). If there are non-applicable
grades (such as those not entered), just click return."""
print "Press return to continue"
raw_input("Continue!")
grade_1 = raw_input("Grade #1: ")
grade_2 = raw_input("Grade #2: ")
grade_3 = raw_input("Grade #3: ")
grade_4 = raw_input("Grade #4: ")
grade_5 = raw_input("Grade #5: ")
grade_6 = raw_input("Grade #6: ")
grade_7 = raw_input("Grade #7: ")
grade_8 = raw_input("Grade #8: ")
if grade_1 == "a+":
grade_1_no = a_1
elif grade_1 == "a":
grade_1_no = a
elif grade_1 == "a-":
grade_1_no = a_2
elif grade_1 == "b+":
grade_1_no = b_1
elif grade_1 == "b":
grade_1_no = b
elif grade_1 == "b-":
grade_1_no = b2
elif grade_1 == "c+":
grade_1_no = c_1
elif grade_1 == "c":
grade_1_no = c
elif grade_1 == "c-":
grade_1_no = c_2
elif grade_1 == "d+":
grade_1_no = d_1
elif grade_1 == "d":
grade_1_no = d
elif grade_1 == "d-":
grade_1_no = d_2
elif grade_1 == "f":
grade_1_no = f
if grade_8 == "a+":
grade_8_no = a_1
elif grade_8 == "a":
grade_8_no = a
elif grade_8 == "a-":
grade_8_no = a_2
elif grade_8 == "b+":
grade_8_no = b_1
elif grade_8 == "b":
grade_8_no = b
elif grade_8 == "b-":
grade_8_no = b_2
elif grade_8 == "c+":
grade_8_no = c_1
elif grade_8 == "c":
grade_8_no = c
elif grade_8 == "c-":
grade_8_no = c_2
elif grade_8 == "d+":
grade_8_no = d_1
elif grade_8 == "d":
grade_8_no = d
elif grade_8 == "d-":
grade_8_no = d_2
elif grade_8 == "f":
grade_8_no = f
if grade_2 == "a+":
grade_2_no = a_1
elif grade_2 == "a":
grade_2_no = a
elif grade_2 == "a-":
grade_2_no = a_2
elif grade_2 == "b+":
grade_2_no = b_1
elif grade_2 == "b":
grade_2_no = b
elif grade_2 == "b-":
grade_2_no = b_2
elif grade_2 == "c+":
grade_2_no = c_1
elif grade_2 == "c":
grade_2_no = c
elif grade_2 == "c-":
grade_2_no = c_2
elif grade_2 == "d+":
grade_2_no = d_1
elif grade_2 == "d":
grade_2_no = d
elif grade_2 == "d-":
grade_2_no = d_2
elif grade_2 == "f":
grade_2_no = f
if grade_3 == "a+":
grade_3_no = a1
elif grade_3 == "a":
grade_3_no = a
elif grade_3 == "a-":
grade_3_no = a_2
elif grade_3 == "b+":
grade_3_no = b_1
elif grade_3 == "b":
grade_3_no = b
elif grade_3 == "b-":
grade_3_no = b_2
elif grade_3 == "c+":
grade_3_no = c_1
elif grade_3 == "c":
grade_3_no = c
elif grade_3 == "c-":
grade_3_no = c_2
elif grade_3 == "d+":
grade_3_no = d_1
elif grade_3 == "d":
grade_3_no = d
elif grade_3 == "d-":
grade_3_no = d_2
elif grade_3 == "f":
grade_3_no = f
if grade_4 == "a+":
grade_4_no = a_1
elif grade_4 == "a":
grade_4_no = a
elif grade_4 == "a-":
grade_4_no = a_2
elif grade_4 == "b+":
grade_4_no = b_1
elif grade_4 == "b":
grade_4_no = b
elif grade_4 == "b-":
grade_4_no = b_2
elif grade_4 == "c+":
grade_4_no = c_1
elif grade_4 == "c":
grade_4_no = c
elif grade_4 == "c-":
grade_4_no = c_2
elif grade_4 == "d+":
grade_4_no = d_1
elif grade_4 == "d":
grade_4_no = d
elif grade_4 == "d-":
grade_4_no = d_2
elif grade_4 == "f":
grade_4_no = f
if grade_5 == "a+":
grade_5_no = a_1
elif grade_5 == "a":
grade_5_no = a
elif grade_5 == "a-":
grade_5_no = a_2
elif grade_5 == "b+":
grade_5_no = b_1
elif grade_5 == "b":
grade_5_no = b
elif grade_5 == "b-":
grade_5_no = b_2
elif grade_5 == "c+":
grade_5_no = c_1
elif grade_5 == "c":
grade_5_no = c
elif grade_5 == "c-":
grade_5_no = c2
elif grade_5 == "d+":
grade_5_no = d1
elif grade_5 == "d":
grade_5_no = d
elif grade_5 == "d-":
grade_5_no = d2
elif grade_5 == "f":
grade_5_no = f
if grade_6 == "a+":
grade_6_no = a_1
elif grade_6 == "a":
grade_6_no = a
elif grade_6 == "a-":
grade_6_no = a_2
elif grade_6 == "b+":
grade_6_no = b_1
elif grade_6 == "b":
grade_6_no = b
elif grade_6 == "b-":
grade_6_no = b_2
elif grade_6 == "c+":
grade_6_no = c_1
elif grade_6 == "c":
grade_6_no = c
elif grade_6 == "c-":
grade_6_no = c_2
elif grade_6 == "d+":
grade_6_no = d_1
elif grade_6 == "d":
grade_6_no = d
elif grade_6 == "d-":
grade_6_no = d_2
elif grade_6 == "f":
grade_6_no = f
if grade_7 == "a+":
grade_7_no = a_1
elif grade_7 == "a":
grade_7_no = a
elif grade_7 == "a-":
grade_7_no = a_2
elif grade_7 == "b+":
grade_7_no = b_1
elif grade_7 == "b":
grade_7_no = b
elif grade_7 == "b-":
grade_7_no = b_2
elif grade_7 == "c+":
grade_7_no = c_1
elif grade_7 == "c":
grade_7_no = c
elif grade_7 == "c-":
grade_7_no = c_2
elif grade_7 == "d+":
grade_7_no = d_1
elif grade_7 == "d":
grade_7_no = d
elif grade_7 == "d-":
grade_7_no = d_2
elif grade_7 == "f":
grade_7_no = f
grades_combined = ((grade_1_no + grade_2_no + grade_3_no + grade_4_no + grade_5_no,
+ grade_6_no + grade_7_no + grade_8_no)/8)
print "Your total GPA is %r" % grades_combined $
这是错误
Traceback (most recent call last):
File "STUDY19", line 252, in <module>
grades_combined = ((grade_1_no + grade_2_no + grade_3_no + grade_4_no + grade_5_no,
NameError: name 'grade_2_no' is not defined $
请大家帮忙！
答案 0 :(得分：3)
试试这个。阅读代码，尝试了解我正在做的事情。阅读Python中的列表和dicts。关于理解。关于循环。
#!/usr/bin/env python
def grade_set(c):
i = ord('d') - ord(c) + 1.0
return [ (c + '+', i+0.4), (c, i), (c + '-', i-0.4) ]
GRADES_NUMBERS = dict(sum([ grade_set(c) for c in 'abcd' ], []))
GRADES_NUMBERS['f'] = 0.0
grades = [ None ] * 8
for i in range(len(grades)):
while True: # until grade is valid
grades[i] = raw_input("Grade #%d: " % (i+1))
if grades[i] in GRADES_NUMBERS:
break
print "This is no valid grade, please repeat."
grades_numbers = [ GRADES_NUMBERS[grade] for grade in grades ]
grades_combined = sum(grades_numbers) / len(grades_numbers)
print "Your total GPA is", grades_combined
计算机的主要思想是让计算机完成重复性任务，而不是程序员。所以一旦你在编程时重复自己，你就会做错事。这在编程界已经深深扎根，他们甚至还有一个首字母缩略词：DRY - Don不要重复自己。
答案 1 :(得分：0)
从我所看到的，您所要做的就是在启动程序之前创建变量名称。 因此，在定义程序之前，只需初始化变量。
grade_no_1 = ''
grade_no_2 = ''
>>>
grade_no_8 = ''
答案 2 :(得分：0)
这不起作用的原因是因为您的变量不存在于else范围之外。看一下这个例子
x = 1
z = 0
if x < 0:
y = 2
else:
z = x + y # this will fail because y does not exist in a place that can be accessed
如果您这样做，它将起作用：
x = 1
y = 0
z = 0
if x < 0:
y = 2
else:
z = x + y
此外，我建议您查看dictionaries或maps，以大大提高代码的可读性。
答案 3 :(得分：0)
非常感谢你，摆脱了我的问题，但创造了另一个问题。我不知道这个错误意味着什么，我认为它与字符串中的正符号有关。我很抱歉这些愚蠢的问题，正如我刚才说的那样，我只有14岁。
Traceback (most recent call last):
File "STUDY19.py", line 261, in <module>
+ grade_6_no + grade_7_no + grade_8_no)/8)
TypeError: bad operand type for unary +: 'str'