CODEWITHSUNDEEP
listconcatenation
Hackxx
Hackxx

Reputation: 71

About adding to lists

def do_something(a, b):
    a.insert(0, 'z')
    b = ['z'] + b
    a = ['a', 'b', 'c']
    a1 = a
    a2 = a[:]
    b = ['a', 'b', 'c']
    b1 = b
    b2 = b[:]

do_something(a, b)

Why does a give ['z' 'a' 'b' 'c'] while b gives ['a' 'b' 'c']? I thought because they're same types they should merge.

Upvotes: 1

Views: 19

Answers (1)

Joni
Joni

Reputation: 111219

b = ['z'] + b creates a new list and makes the local variable b point to it. The original list is not modified.

In contrast, the insert method changes the existing list, so its effects can be seen outside of your function.

Upvotes: 1

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