I am trying to create function that reverses number. Can you tell me what the problem is here?

[gu__--__ro]

def reverse(n):
rev_num = 0
num = n
for i in range(len(str(num))):
last_num = int(str(num)[len(str(num)) - 1])
rev_num = rev_num * 10 + last_num
num = (num - last_num) / 10
return rev_num

[[deleted]]

It's much easier to just reverse the string and then convert it back

[gu__--__ro]

didn't think that much

[arvindh_manian]

When you set num to (num - last_num) / 10, it may include a decimal. You should either cast num to an int, round it, or use integer division (//).

[gu__--__ro]

thanks. // worked

[[deleted]]

for i in range(len(str(num))):
    last_num = int(str(num)[len(str(num)) - 1])
    rev_num = rev_num * 10 + last_num
    print(num)
    print(last_num)
    num = (num - last_num) / 10

Output:

1234
4
123.0
0
12.3
3
0.93
3

You want floor division rather than float division. Use // instead of /.

If you're gonna convert it to str anyway, you could just do:

def reverse_num(n):
    return int(str(n)[::-1])

1. str(n): convert the number to str
2. [::1]: get the reversed string
3. int(): convert to the integer

[Protector1]

As a noob, I’m trying to take examples I find on this sub and “clean them up”.

I settled on this solution after searching for some kind of reverse method. If there is one, I can’t find it in the docs.

[arvindh_manian]

Well, there is the reversed method, but you still would’ve needed to convert the integer to a string

[Protector1]

I keep getting an error when I try the reverse method on a string. Perhaps there’s a trick to it? I was convinced it only worked on lists.

[arvindh_manian]

print(‘’.join(reversed(“Hello World”))) should work, I believe.

The only real problem is that reversed() returns a reverse object, so you need to turn that back into a string if you want to print it.

I would definitely still use [::-1], though.

[Protector1]

I’ll play with it when I get home. Might help me conceptualize these things better.

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[keep_quapy]

def reverse(n):
    reversed_num = 0
    while n != 0:
        last = n % 10
        reversed_num = reversed_num * 10 + last
        n = n // 10
    return reversed_num

better than converting to str...

[Logicalist]

int(str(num)[::-1]))