Questions about massive

Question

Hello guys, sorry for my English and stupidity :)

here is the question:

num1=[1,2,3,4]
num2=num1
num2[0]=9
print ("num1 is: ", num1, "\nnum2 is: ", num2)

why if I change one of them (num1 or num2) they both change? num1[0]=0 and num2[0]=0 too. Why does it happens? I've changed only num2, not num1

Thank you in advance

Answer 1

python works with a method called object sharing. this means that when you assign a variable to be another one, it will exactly be the same object. you need to make a copy in order to do what you want, i dont recall the functions name, but it should not be very difficult to search for it.

edit: here you go, https://docs.python.org/2/library/copy.html

Answer 2

a number is not an object. a list or set is though. you should read the python docs. it is all well explained

Answer 3

To Testing003

Ok then. But if I follow the same logic for this code

a=2
b=a
a=7
print(b)

I will get result b=7, but it is false. True is that b = 2 (((

Answer 4

To Testing003.

Ok. Thank you very much! Sorry about this stupid question please :)