'append' works but 'extend' fails to work in this case

Question

I was trying to add a value to each of the elements in a list. Here's the code:

c = [1,2,3]
d= []
for i in range(len(c)):
    d.append(c[i]+3)
print (d)

The code just works fine. But if I change it to 'extend' as follows:

c = [1,2,3]
d= []
for i in range(len(c)):
    d.extend(c[i]+3)
print (d)

it would throw a TypeError:

TypeError: 'int' object is not iterable

May I know why is it so?

Possible duplicate of [Difference between append vs. extend list methods in Python](https://stackoverflow.com/questions/252703/difference-between-append-vs-extend-list-methods-in-python) — Thierry Lathuille, Aug 12 '18 at 07:15

score 1 · Accepted Answer · answered Aug 12 '18 at 15:55

1

extend() takes a list as its required parameter. You are giving it an int. Try this:

c = [1,2,3]
d= []
for i in range(len(c)):
    d.extend([c[i]+3])
print(d)

answered Aug 12 '18 at 15:55

dustintheglass

1 Answers1