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这个问题已经有了答案:
- UnboundLocalError in Python [duplicate] 8 answers
- Python中的UnboundLocalError [duplicate] 8个答案
if execute the following code will show error message:
如果执行下列代码将显示错误消息:
UnboundLocalError: local variable 'a' referenced before assignment
UnboundLocalError:在赋值之前引用的本地变量“a”
a = 220.0
b = 4300.0
c = 230.0/4300.0
def fun():
while (c > a/b):
a = a + 1
print a/b
if __name__ == '__main__':
fun()
but modify to :
但修改:
a = 220.0
b = 4300.0
c = 230.0/4300.0
def fun():
aa = a
bb = b
while (c > aa/bb):
aa = aa + 1
print aa/bb
if __name__ == '__main__':
fun()
it will fine. Any advice or pointers would be awesome. Thanks a lot!
它会很好。任何建议或建议都会很棒。谢谢!
1 个解决方案
#1
9
You can't modify a global variable without using the global statement:
如果不使用全局语句，就不能修改全局变量:
def fun():
global a
while (c > a/b):
a = a + 1
print a/b
As soon as python sees an assignment statement like a = a + 1 it thinks that the variable a is local variable and when the function is called the expression c > a/b is going to raise error because a is not defined yet.
当python看到像a = a + 1这样的赋值语句时，它会认为变量a是局部变量，当函数被称为表达式c > a/b时，会引起错误，因为a还没有定义。
#1
9
You can't modify a global variable without using the global statement:
如果不使用全局语句，就不能修改全局变量:
def fun():
global a
while (c > a/b):
a = a + 1
print a/b
As soon as python sees an assignment statement like a = a + 1 it thinks that the variable a is local variable and when the function is called the expression c > a/b is going to raise error because a is not defined yet.
当python看到像a = a + 1这样的赋值语句时，它会认为变量a是局部变量，当函数被称为表达式c > a/b时，会引起错误，因为a还没有定义。