why is the code giving different result when I am explicitly defining the value variable in a decimal to binary recursive function?

Question

Here i declared value=value//2

def dec2bin(value,lis=[]):
    if value>1:
        value=value//2
        dec2bin(value)
    lis.append(value%2)
    return lis
    
print(dec2bin(5))

returns [1,1,0]

Here I just used value//2 within the function

def dec2bin(value,lis=[]):
    if value>1:
        dec2bin(value//2)
    lis.append(value%2)
    return lis
    
print(dec2bin(5))

returns [1,0,1]

Try `print(value, lis)` before entering recursion, to see how values evolve in time. — CristiFati, Aug 03 '21 at 07:33
You are assigning ```value``` as ```value//2``` But simply doing ```value//2``` will not change the value of ```value``` — , Aug 03 '21 at 07:33

score 1 · Answer 1 · answered Aug 03 '21 at 08:01

There are many things wrong here. The most surprising is probably "Least Astonishment" and the Mutable Default Argument which means that lis=[] probably doesn't do what you expect here.

Secondly, you are not recording the result from your recursive call.

Try this instead:

def dec2bin(value):
      lis = []
      if value > 1:
        lis = dec2bin(value//2)
      lis.append(value % 2)
      return lis

why is the code giving different result when I am explicitly defining the value variable in a decimal to binary recursive function?

1 Answers1