Yield generator

Question

I didn't understand why I can't use list in first yield example ( I tried and got error) but I can do so in second one.

First
def countdown():
i=5
while i > 0:
yield i
i -= 1

for i in countdown():
print(i)

Second
def numbers(x):
for i in range(x):
if i % 2 == 0:
yield i

print(list(numbers(11)))

Answer 1

I'm not sure to good understanding your problem...

are you trying to do:

print(list(countdown()))

Answer 2

however, you could do simpler to get same result:

print(list(range(5,0,-1)))

usefulness of generators are revealed by using them for more complex cases ;P

Answer 3

The result of first code was
5
4
3
2
1
I wanted to see if I could get it as [5, 4, 3, 2, 1] but faced error

Answer 4

visph
Thanks... but I still don't get usefulness of yield function. I mean I could have gotten the result of first code by using below instead.

i = 5
while i >0:
print(i)
i = i -1

Answer 5

Okz... thanks for help.

Answer 6

try my code: it works as you expect ;)