This question already has answers here :
Because you're assigning an output to the act of appending which has no output, so instead of:
a=a.append(5)
you just want
a.append(5)
Why does append() always return None in Python?, This is the function I used here, it returned 'None'. I think you want to .append() the list after the powers in powers loop (where it is at Thank you for the tip, I didn't realise my code would be copied as flat text, but you did get� list.append is a method that modifies the existing list. It doesn't return a new list -- it returns None , like most methods that modify the list. Simply do aList.append('e') and your list will get the element appended.
This just indicates that the "append" method does not return anything. It only modifies the existing list. It does not return an updated list.
Don't bother doing a = a.append(4). If you just want to add an entry to the list, do a.append(4) to modify a.
Why does `list.append()` return `none`?, The append method of list adds the specified item to the end of the list from which it is called, then return s None . Instead of this: lst = lst.append(� In fact, it turned out from some googling that Python functions have a default return value, which is None if no return expression is given, or return is given on its own. For example, the source code for the append() method of list is this: In the CPython source, this is in. Objects/listobject.c
I try to explain in the easiest way:
With:
a.append(5)
you are calling the function that adds something (in this case 5 ) to a
With:
a = a.append(5)
you are saying that a is equal the result of the funcion .append() . But
append just modifies an existing list, it does not returns anything, and it does not, as you thought, return a new list with the element appended.
Why my function is returning None in this example?, append() does not actually return a list, it merely updates the list object in place. ( I.e. there is no return value from the function. Other programming� Python habitually returns None from functions and methods that mutate the data, such as list.sort, list.append, and random.shuffle, with the idea being that it hints to the fact that it was mutating. If you want to take an iterable and return a new, sorted list of its items, use the sorted builtin function.
Why do Python functions return None?, append is a mutating (destructive) operation (it modifies the list in place my guess is that if append returned the newly modified list, users might think that it was It is a convention in Python that methods that mutate sequences return None . to answer your question, my guess is that if append returned the newly modified list, users might think that it was non-destructive, ie they might write code like m = l.append ("a") n = l.append ("b") and expect n to be [1,2,3,"b"] It is a convention in Python that methods that mutate sequences return None.
Why does append() always return None in Python?, my head: "[list.append()] returns None and updates the list in place.". Seems like this is how Python works, though I can't (easily) find it listed anywhere. A list is mutable and calling a method that mutates the list doesn't� Python list method append() appends a passed obj into the existing list. Syntax. Following is the syntax for append() method − list.append(obj) Parameters. obj − This is the object to be appended in the list. Return Value. This method does not return any value but updates existing list. Example. The following example shows the usage of
Section 14, Values like None, True and False are not strings: they are special values in Python, But if the function should return a value, make sure all execution paths do We often want to know if some condition holds for any item in a list, e.g. “ does one random number xs.append(num) # Save it in our list tot = sum(xs) return tot� append() Parameters. The method takes a single argument. item - an item to be added at the end of the list; The item can be numbers, strings, dictionaries, another list, and so on.
Comments This is factually incorrect. If the append returned "the function of adding something to a list", then you would be able to call the result as a function. It is not doing that; it's simply returning nothing. Saying a = function() (where function() returns 1) is the same as a = 1. So if .append() returns None , a = append(5) will return None as well. However I tried to explain it better That's true, but your statement "a is equal to the function of adding something to the list" is still misleading because a will not equal any kind of function. This is a distinction that is very important because variables can equal functions in Python, and it is very common to have functions return functions (decorators, for example). Yeah, you're right, what I wanted to say is "a is equal to the result of the funcion of adding something to the list" I think your latest edit helps a lot and makes it clear what you're trying to say.
