Python中的排序列表导致错误

Question

I'm having a problem sorting list in Python here's my code:

lista = [ 1, .89, .65, .90]

for x in lista.sort():
    print (x)

Error is:

TypeError: 'NoneType' object is not iterable

Answer 1

The sort method sorts the list in-place; it always returns None . What you can do:

lista = [ 1, .89, .65, .90]
lista.sort()

for x in lista:
    print (x)

Or, as @Delgan pointed out, you can use the sorted function, which returns the sorted list:

lista = [ 1, .89, .65, .90]

for x in sorted(lista):
    print (x)

Answer 2

.sort() doesn't return anything. If you want to modify the list to be sorted you can do

lista = [ 1, .89, .65, .90]
lista.sort()
for x in lista:
    print (x)

or if you want to keep the list in the original order you can use sorted which returns a new list of the sorted elements:

lista = [ 1, .89, .65, .90]

for x in sorted(lista):
    print (x)

Answer 3

list.sort() only change the list but return None, you need:

lista = [1, .89, .65, .90]
lista.sort()

for x in lista:
    print(x)

Or simply use sorted() :

lista = [1, .89, .65, .90]

for x in sorted(lista):
    print (x)

sorted() return a new list but sorted, note that it doesn't change the current list.