Common errors and messages, Python Programming

Common Errors and Messages

Here are some common Python errors  and error  messages to look  out for. Please let us give if you have any favorite additions for this list.

  • A problem about NoneType often means you forgot a return.

def plus1 (x):

 

x + 1

>>> y = plus1(x)

>>> plus1(x) + 2

Traceback (most recent call last):

File "", line 1, in

TypeError that shows: unsupported operator type(s) for +: 'NoneType' and 'int'

 

  • Weird results from math can give from integer division

>>> 3/ 9

0

  • "Unsubscriptable object" seems you are trying to get an element out of something that isn't a dictionary, list, or tuple.

 

>>> x = 1

>>> x[3]

Traceback (most recent call last):

File "", line 1, in

TypeError that shows: 'int' object is unsubscriptable

 

  • "Object is not callable" defines that you are trying to use something that isn't a procedure or method as if it were.

 

>>> x = 1

>>> x(3)

Traceback (most recent call last):

File "", line 1, in

TypeError that shows: 'int' object is not callable

 

  • "List index out of range" describes that you are trying to read or write an element of a list that is not present.

 

>>> a = range(5)

>>> a

[0, 1, 2, 3, 4]

>>> a[5]

Traceback (most recent call last):

File "", line 1, in

IndexError that shows: list index out of range

 

  • "Maximum recursion depth exceeded" produces the error has a recursive procedure that is nested your parent case is not being reached due to a bug.

 

def fizz(x):

return fizz(x - 1)

>>> fizz(10)

Traceback (most recent call last): File "", line 1, in File "", line 2, in fizz

File "", line 2, in fizz

...

File "", line 2, in fizz

RuntimeError that shows message: maximum recursion depth exceeded

 

  • "Key Error " defines that you are trying to look up an element in a dictionary that is not present.

 

>>> d = {'a':7, 'b':8}

>>> d['c']

Traceback (most recent call last):

File "", line 1, in

KeyError: 'c'

 

 

  • Another common error is forgetting the self before calling a function. This creates the same error that you would get if you tried to call a function that wasn't de?ned at all.

Traceback (most recent call last): File "", line 1, in File "V2.py", line 22, in  

 

add    

return add(v)

NameError: global name 'add' is not defined

 

 

Posted Date: 8/9/2012 7:22:12 AM | Location : United States







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