发布于 2014-12-21 09:56:56 | 4787 次阅读 | 评论: 1 | 来源: PHPERZ
Python编程语言
Python 是一种面向对象、解释型计算机程序设计语言，由Guido van Rossum于1989年底发明，第一个公开发行版发行于1991年。Python语法简洁而清晰，具有丰富和强大的类库。它常被昵称为胶水语言，它能够把用其他语言制作的各种模块（尤其是C/C++）很轻松地联结在一起。
本文为大家整理总结了一些常见的python错误大全，感兴趣的同学参考下。
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In [105]: T1 = (1)
In [106]: T2 = (2,3)
In [107]: T1 + T2
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-107-b105c7b32d90> in <module>()
----> 1 T1 + T2;
TypeError: unsupported operand type(s) for +: 'int' and 'tuple'
【错误分析】(1)的类型是整数，所以不能与另一个元祖做合并操作，如果只有一个元素的元祖，应该用(1,)来表示
In [108]: type(T1)
Out[108]: int
In [109]: T1 = (1,)
In [110]: T2 = (2,3)
In [111]: T1 + T2
Out[111]: (1, 2, 3)
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>>> hash(1,(2,[3,4]))
Traceback (most recent call last):
File "<pyshell#95>", line 1, in <module>
hash((1,2,(2,[3,4])))
TypeError: unhashable type: 'list'
【错误分析】字典中的键必须是不可变对象，如(整数，浮点数，字符串，元祖)，可用hash()判断某个对象是否可哈希
>>> hash('string')
-1542666171
但列表中元素是可变对象，所以是不可哈希的，所以会报上面的错误.如果要用列表作为字典中的键，最简单的办法是:
>>> D = {}
>>> D[tuple([3,4])] = 5
>>> D
{(3, 4): 5}
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>>> L = [2,1,4,3]
>>> L.reverse().sort()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'sort'
>>> L
[3, 4, 1, 2]
【错误分析】列表属于可变对象,其append(),sort(),reverse()会在原处修改对象，不会有返回值，或者说返回值为空，
所以要实现反转并排序，不能并行操作，要分开来写
>>> L = [2,1,4,3]
>>> L.reverse()
>>> L.sort()
>>> L
[1, 2, 3, 4]
或者用下面的方法实现:
In [103]: sorted(reversed([2,1,4,3]))
Out[103]: [1, 2, 3, 4]
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>>> class = 78
SyntaxError: invalid syntax
【错误分析】class是Python保留字，Python保留字不能做变量名，可以用Class，或klass
同样，保留字不能作为模块名来导入，比如说，有个and.py，但不能将其作为模块导入
>>> import and
SyntaxError: invalid syntax
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>>> f = open('D:\new\text.data','r')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IOError: [Errno 22] invalid mode ('r') or filename: 'D:\new\text.data'
>>> f = open(r'D:\new\text.data','r')
>>> f.read()
'Very\ngood\naaaaa'
【错误分析】\n默认为换行，\t默认为TAB键，所以在D:\目录下找不到ew目录下的ext.data文件，将其改为raw方式输入即可。
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try:
print 1 / 0
except ZeroDivisionError:
print 'integer division or modulo by zero'
finally:
print 'Done'
else:
print 'Continue Handle other part'
报错如下:
D:\>python Learn.py
File "Learn.py", line 11
else:
^
SyntaxError: invalid syntax
【错误分析】错误原因，else, finally执行位置;正确的程序应该如下:
try:
print 1 / 0
except ZeroDivisionError:
print 'integer division or modulo by zero'
else:
print 'Continue Handle other part'
finally:
print 'Done'
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>> [x,y for x in range(2) for y in range(3)]
File "<stdin>", line 1
[x,y for x in range(2) for y in range(3)]
^
SyntaxError: invalid syntax
【错误分析】错误原因，列表解析中，x,y必须以数组的方式列出(x,y)
>>> [(x,y) for x in range(2) for y in range(3)]
[(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2)]
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class JustCounter:
__secretCount = 0
def count(self):
self.__secretCount += 1
print 'secretCount is:', self.__secretCount
count1 = JustCounter()
count1.count()
count1.count()
count1.__secretCount
报错如下:
>>>
secretCount is: 1
secretCount is: 2
Traceback (most recent call last):
File "D:\Learn\Python\Learn.py", line 13, in <module>
count1.__secretCount
AttributeError: JustCounter instance has no attribute '__secretCount'
【错误分析】双下划线的类属性__secretCount不可访问，所以会报无此属性的错误.
解决办法如下:
# 1. 可以通过其内部成员方法访问
# 2. 也可以通过访问
ClassName._ClassName__Attr
#或
ClassInstance._ClassName__Attr
#来访问，比如：
print count1._JustCounter__secretCount
print JustCounter._JustCounter__secretCount
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>> print x
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'x' is not defined
>>> x = 1
>>> print x
1
【错误分析】Python不允许使用未赋值变量
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>>> t = (1,2)
>>> t.append(3)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'append'
>>> t.remove(2)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'remove'
>>> t.pop()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'tuple' object has no attribute 'pop'
【错误分析】属性错误,归根到底在于元祖是不可变类型，所以没有这几种方法.
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>>> t = ()
>>> t[0]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: tuple index out of range
>>> l = []
>>> l[0]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: list index out of range
【错误分析】空元祖和空列表，没有索引为0的项
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>>> if X>Y:
... X,Y = 3,4
... print X,Y
File "<stdin>", line 3
print X,Y
^
IndentationError: unexpected indent
>>> t = (1,2,3,4)
File "<stdin>", line 1
t = (1,2,3,4)
^
IndentationError: unexpected indent
【错误分析】一般出在代码缩进的问题
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>>> f = file('1.txt')
>>> f.readline()
'AAAAA\n'
>>> f.readline()
'BBBBB\n'
>>> f.next()
'CCCCC\n'
【错误分析】如果文件里面没有行了会报这种异常
>>> f.next() #
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
StopIteration
有可迭代的对象的next方法,会前进到下一个结果,而在一系列结果的末尾时,会引发StopIteration的异常.
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>>> string = 'SPAM'
>>> a,b,c = string
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: too many values to unpack
【错误分析】接受的变量少了，应该是
>>> a,b,c,d = string
>>> a,d
('S', 'M')
#除非用切片的方式
>>> a,b,c = string[0],string[1],string[2:]
>>> a,b,c
('S', 'P', 'AM')
或者
>>> a,b,c = list(string[:2]) + [string[2:]]
>>> a,b,c
('S', 'P', 'AM')
或者
>>> (a,b),c = string[:2],string[2:]
>>> a,b,c
('S', 'P', 'AM')
或者
>>> ((a,b),c) = ('SP','AM')
>>> a,b,c
('S', 'P', 'AM')
简单点就是:
>>> a,b = string[:2]
>>> c = string[2:]
>>> a,b,c
('S', 'P', 'AM')
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>>> mydic={'a':1,'b':2}
>>> mydic['a']
1
>>> mydic['c']
Traceback (most recent call last):
File "<stdin>", line 1, in ?
KeyError: 'c'
【错误分析】当映射到字典中的键不存在时候，就会触发此类异常, 或者可以，这样测试
>>> 'a' in mydic.keys()
True
>>> 'c' in mydic.keys() #用in做成员归属测试
False
>>> D.get('c','"c" is not exist!') #用get或获取键，如不存在，会打印后面给出的错误信息
'"c" is not exist!'
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File "study.py", line 3
return None
^
dentationError: unexpected indent
【错误分析】一般是代码缩进问题，TAB键或空格键不一致导致
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>>>def A():
return A()
>>>A() #无限循环，等消耗掉所有内存资源后，报最大递归深度的错误
File "<pyshell#2>", line 2, in A return A()RuntimeError: maximum recursion depth exceeded
class Bird:
def __init__(self):
self.hungry = True
def eat(self):
if self.hungry:
print "Ahaha..."
self.hungry = False
else:
print "No, Thanks!"
该类定义鸟的基本功能吃，吃饱了就不再吃
输出结果:
>>> b = Bird()
>>> b.eat()
Ahaha...
>>> b.eat()
No, Thanks!
下面一个子类SingBird,
class SingBird(Bird):
def __init__(self):
self.sound = 'squawk'
def sing(self):
print self.sound
输出结果:
>>> s = SingBird()
>>> s.sing()
squawk
SingBird是Bird的子类，但如果调用Bird类的eat()方法时,
>>> s.eat()
Traceback (most recent call last):
File "<pyshell#5>", line 1, in <module>
s.eat()
File "D:\Learn\Python\Person.py", line 42, in eat
if self.hungry:
AttributeError: SingBird instance has no attribute 'hungry'
【错误分析】代码错误很清晰,SingBird中初始化代码被重写，但没有任何初始化hungry的代码
class SingBird(Bird):
def __init__(self):
self.sound = 'squawk'
self.hungry = Ture #加这么一句
def sing(self):
print self.sound
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class Bird:
def __init__(self):
self.hungry = True
def eat(self):
if self.hungry:
print "Ahaha..."
self.hungry = False
else:
print "No, Thanks!"
class SingBird(Bird):
def __init__(self):
super(SingBird,self).__init__()
self.sound = 'squawk'
def sing(self):
print self.sound
>>> sb = SingBird()
Traceback (most recent call last):
File "<pyshell#5>", line 1, in <module>
sb = SingBird()
File "D:\Learn\Python\Person.py", line 51, in __init__
super(SingBird,self).__init__()
TypeError: must be type, not classobj
【错误分析】在模块首行里面加上__metaclass__=type，具体还没搞清楚为什么要加
__metaclass__=type
class Bird:
def __init__(self):
self.hungry = True
def eat(self):
if self.hungry:
print "Ahaha..."
self.hungry = False
else:
print "No, Thanks!"
class SingBird(Bird):
def __init__(self):
super(SingBird,self).__init__()
self.sound = 'squawk'
def sing(self):
print self.sound
>>> S = SingBird()
>>> S.
SyntaxError: invalid syntax
>>> S.
SyntaxError: invalid syntax
>>> S.eat()
Ahaha...
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>>> T
(1, 2, 3, 4)
>>> T[0] = 22
Traceback (most recent call last):
File "<pyshell#129>", line 1, in <module>
T[0] = 22
TypeError: 'tuple' object does not support item assignment
【错误分析】元祖不可变，所以不可以更改;可以用切片或合并的方式达到目的.
>>> T = (1,2,3,4)
>>> (22,) + T[1:]
(22, 2, 3, 4)
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