Trying to write code for converting decimal number into binary but it is showing output ending with "none"

Question

like if input is "4"....it is generating output as "100None"

def D_to_B(n)
binaryNum = [0] * n;
i = 0;
while (n > 0):
binaryNum[i] = n % 2;
n = int(n / 2);
i += 1;

for j in range(i - 1, -1,-1):
print(binaryNum[j], end = "");

if __name__ == '__main__':
n = int(input().strip())
result = D_to_B(n)
print (result)

Answer 1

Here's an idea of implementation where D_to_B() returns a string forged by merging list elements

https://code.sololearn.com/c5TM409HCwec/?ref=app

+ Added comments for explanation

Answer 2

Remove last 2 lines. Just put
D_to_B(n)

You are not returning anything explicitly from function so implicitly it returns none. Don't catch it.

Answer 3

Instead of printing reverse in function, return the result.

And yes.. Instead of using list, better to use a string.
binaryNum = ""

and add by
binaryNum += str( n%2 )

and your need
return binaryNum
reverse string is binaryNum[::-1]

Answer 4

Adding to Jayakrishna - I would rather suggest you to try and find another way to do this - assuming it's for educational purpose such that you are not allowed to use built-in functions like bin()

From data efficiency PoV, there's a lot of wasted memory using this approach.

Try to convert 2048 to binary - you'll be creating a list with 2048 zeroes in,.while actually, 2048 can fit in just 12.

I'm sure you understand ...

Answer 5

Keeping the last block of code as it is, How can we made changes in above code so that this "None" problem can be solved?
@jayakrishnain
@Ipang

Answer 6

Did you mean to keep the code in __main__ or in the D_to_B()

Minimum modification is as Jayakrishna stated - just call D_to_B(n) but don't pass it as argument for print()

That way code works, with minimum revision.

But I'd still rather suggest you find a better approach (algorithm) in doing this, for better plan of memory utilisation.

Answer 7

First, add ":" in the function definition.

Your function prints, so you essentially get a print(print()) ☺️

Debug:
out = ''
for j in range(i - 1, -1,-1):
out += str(binaryNum[j])
return out

Answer 8

Hello

Answer 9

I'm new to all this