Function editing lists in Python -

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• how pass variable reference? 22 answers

so i've observed in python3 if like

a = 5 def addfive(x):     x+=5     return x print(addfive(a),a) 

the output "10 5" since not changed function. same not happen lists:

a = [1,2,3]  def b(x):     z = x     z.append(10)  b(a) print(a) 

when run function changes actual list.

now question: why happen, can read more this(honestly have no idea how word google search) , how can avoid this. please feel free redirect me other articles common problem couldn't find similar.

thanks in advance :)

use copy module.

import copy  = [1,2,3]  def b(x):     z = copy.deepcopy(x)     z.append(10)     return z  b(a) print(a) 

this prints

[1, 2, 3, 10] [1, 2, 3]