有人可以解释输出吗？

Question

q =["hello", "there"]
q.insert(2,"How r u")
print("Result : "),q

OUTPUT:

Result :

(None, ['hello', 'there', 'How r u'])

Why it prints None ?

Answer 1

print("Result : "),q

应该

print("Result : ", q)

Answer 2

Because print returns None .

For example :

>>> print(print(1))
1
None

First it prints value and then returns None .

Explaining your code :

q =["hello", "there"]
q.insert(2,"How r u")
print(print("Result : "),q)

Steps :

Start from inner print :

print("Result : ") # -> prints Result :  and returns None

Now it becomes:

print(None, q) # -> prints None ['hello', 'there', 'How r u']   

Answer 3

Every list of var names in python are in reality a tuple, so:

a, b is really (a, b)

so

print("Result : "),q is a tuple of values (None, q)