我正在编写以下代码。当我尝试在每个if / elif缩进中使用全局变量时，我收到一个错误，指出该变量在变为全局之前已被使用。如果我只在第一个if中使用全局，我会收到一个错误，指的是无法在本地编辑局部变量这一事实。
以下代码是我能够正常工作的最远的代码。调试时，此代码不会导致任何错误，只有运行时的回调错误。
global daycountone
global daycounttwo
global y
print("Input date using numbers only")
print("Ex. Day: 13")
print(" Month: 4")
print(" Year: 2009")
dayone = input("Day ")
monthone = input("Month ")
yearone = input("Year ")
print("Input another date, still using numbers only")
print("Ex. Day: 13")
print(" Month: 4")
print(" Year: 2009")
daytwo = input("Day: ")
monthtwo = input("Month: ")
yeartwo = input("Year: ")
y = yearone
while(y>0):
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 366
else:
daycountone = daycountone + 365
else:
daycountone = daycountone + 365
else:
daycountone = daycountone + 366
y = y-1
while(y>0):
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 366
else:
daycounttwo = daycounttwo + 365
else:
daycounttwo = daycounttwo + 365
else:
daycounttwo = daycounttwo + 366
y = y-1
if(monthone == 2):
daycountone = daycountone + 31
elif(monthone == 3):
daycountone = daycountone + 59
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
elif(monthone == 4):
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
daycountone = daycountone + 90
elif(monthone == 5):
daycountone = daycountone + 120
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
elif(monthone == 6):
daycountone = daycountone + 151
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
elif(monthone == 7):
daycountone = daycountone + 181
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
elif(monthone == 8):
daycountone = daycountone + 212
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
elif(monthone == 9):
daycountone = daycountone + 243
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
elif(monthone == 10):
daycountone = daycountone + 273
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
elif(monthone == 11):
daycountone = daycountone + 304
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
elif(monthone == 12):
daycountone = daycountone + 334
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
if(monthtwo == 2):
daycounttwo = daycounttwo + 31
elif(monthtwo == 3):
daycounttwo = daycounttwo + 59
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 1
else:
daycounttwo = daycounttwo + 1
elif(monthtwo == 4):
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 1
else:
daycounttwo = daycounttwo + 1
daycounttwo = daycounttwo + 90
elif(monthtwo == 5):
daycounttwo = daycounttwo + 120
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 1
else:
daycounttwo = daycounttwo + 1
elif(monthtwo == 6):
daycounttwo = daycounttwo + 151
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycountone = daycountone + 1
else:
daycountone = daycountone + 1
elif(monthtwo == 7):
daycounttwo = daycounttwo + 181
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 1
else:
daycounttwo = daycounttwo + 1
elif(monthtwo == 8):
daycounttwo = daycounttwo + 212
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 1
else:
daycounttwo = daycounttwo + 1
elif(monthtwo == 9):
daycounttwo = daycounttwo + 243
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 1
else:
daycounttwo = daycounttwo + 1
elif(monthtwo == 10):
daycounttwo = daycounttwo + 273
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 1
else:
daycounttwo = daycounttwo + 1
elif(monthtwo == 11):
daycounttwo = daycounttwo + 304
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 1
else:
daycounttwo = daycounttwo + 1
elif(monthtwo == 12):
daycounttwo = daycounttwo + 334
if(y%4 == 0):
if(y%100 == 0):
if(y%400 == 0):
daycounttwo = daycounttwo + 1
else:
daycounttwo = daycounttwo + 1
daycountone = daycountone + dayone
daycounttwo = daycounttwo + daytwo
daysbetween = daycounttwo - daycountone
if(daysbetween<0):
daysbetween = -1 * daysbetween
prnt = 'The number of days between the two dates is ' + daysbetween + 'days exactly, accounting for leap years'
print prnt
答案 0 :(得分：0)
Python基本上遵循功能范围：请参阅Short Description of the Scoping Rules?
因为你没有函数，所以你不需要全局变量。当您确实需要使用全局变量时，可以在第一次读取的本地范围内声明它们。例如：
SOME_COUNTER = 0
def some_func(some_num):
global SOME_COUNTER
SOME_COUNTER += some_num
some_func(3)
print SOME_COUNTER # 3
some_func(2)
print SOME_COUNTER # 5
def some_other_func(some_num):
SOME_COUNTER += some_num # this won't work; SOME_COUNTER isn't in scope
some_other_func(3) # blows up with an UnboundLocalError saying SOME_COUNTER was used before definition (i.e. it isn't in scope)
答案 1 :(得分：0)
全局变量可以让你修改函数中的一个变量，但因为你没有使用任何函数，所以你不需要做任何全局变量。
可以更轻松地完成此操作