Here's the code1:
x = [0, 1]
i = 0
j=0
i,x[i]=1,2
#print i,x
#1,[0,2]
Here's the code2:
x=0
y=1
x,y=3,x
#print x,y
#3,0
i know that python is assign variables at the same time when there are mutiple variables need to assignment.
but why the result of code1 is 1,[0,2]?shouldn't it be 1,[2,1]-- not the same time ?
I mean assign x[i],variable "i" should be 0,cuz "that time" variable "i" is 0,so it should be i,x[0]=1,2. But it is not. :(
You understanding is a bit wrong , Python does not assign the variables at the same time , it's just that the right hand side is first evaluated completely before assignment starts, and only after that assignment to left hand side starts , the assignment to left hand side is still sequential internally , so in first case i's value is changed before it is used again in 'x[i]' .
The difference in the first place comes because you are changing and using value of 'I' in the left hand side .