python - sort() and reverse() functions do not work -

i trying test how lists in python works according tutorial reading. when tried use list.sort() or list.reverse(), interpreter gives me none.

please let me know how can result these 2 methods:

a = [66.25, 333, 333, 1, 1234.5] print(a.sort()) print(a.reverse()) 

.sort() , .reverse() change list in place , return none see mutable sequence documentation:

the sort() , reverse() methods modify list in place economy of space when sorting or reversing large list. remind operate side effect, don’t return sorted or reversed list.

do instead:

a.sort() print(a) a.reverse() print(a) 

or use sorted() , reversed() functions.

print(sorted(a))               # sorted print(list(reversed(a)))       # reversed print(a[::-1])                 # reversing using negative slice step print(sorted(a, reverse=true)) # sorted *and* reversed 

these methods return new list , leave original input list untouched.

demo, in-place sorting , reversing:

>>> = [66.25, 333, 333, 1, 1234.5] >>> a.sort() >>> print(a) [1, 66.25, 333, 333, 1234.5] >>> a.reverse() >>> print(a) [1234.5, 333, 333, 66.25, 1] 

and creating new sorted , reversed lists:

>>> = [66.25, 333, 333, 1, 1234.5] >>> print(sorted(a)) [1, 66.25, 333, 333, 1234.5] >>> print(list(reversed(a))) [1234.5, 1, 333, 333, 66.25] >>> print(a[::-1]) [1234.5, 1, 333, 333, 66.25] >>> print(sorted(a, reverse=true)) [1234.5, 333, 333, 66.25, 1] >>>  # input list untouched [66.25, 333, 333, 1, 1234.5]