Sorting lists in python issue -

i started learning python few days ago (with no prior programming experience nor knowledge) , stuck following thing not understand: let' have unsorted list "b" , want sort list "c" looks list "b":

b = [4,3,1,2] c=b c.sort()  print b print c 

what discovered both b , c sorted: [1,2,3,4] [1,2,3,4]

why so?

it seems solution works when create copy of "b" list:

b = [4,3,1,2] c=b[:] c.sort()  print b print c 

results in: [4,3,1,2] [1,2,3,4]

but why first solution not work?

thank you.

in first sample, copying b c reference, means whenever change (sorting, example) made on b, applied on c, because both point same object.

in second sample, copying array by value, not by reference, create entirely new object in memory. therefore, changes made on 1 of them not applied on other one.