String concatenation in while loop not working

There are a few issues with the code you’ve provided:

1. x starts with a value of (), and in any case, rather than concatenating strings to it, you’re adding numbers within the loop.
2. You’re trying to append the numbers rather than prepend, so the result would be reversed if it worked.
3. Your second print is not inside the conditional, so the output is duplicated.

What you need to do is initialize x with an empty string and then prepend strings to it:

working = int(input("Please enter a non-negative decimal number to convert to binary: "))
x = ""

while working != 0:
    remainder = working % 2
    working = working // 2

    if remainder == 0:
        x = "0" + x
    else:
        x = "1" + x

    print (working, x)

print ("I believe your binary number is", x)

Output:

λ python convert-to-binary.py
Please enter a non-negative decimal number to convert to binary: 76
38 0
19 00
9 100
4 1100
2 01100
1 001100
0 1001100
I believe your binary number is 1001100

The problem is that you are not working with strings. You are first creating an empty tuple for x, and then overwriting that with an integer value later.

To do what you are attempting, you need to treat x as a string, and append the string literals '0' and '1' to it.

Try this instead:

working = int(input("Please select a non-negative decimal number to convert to binary.  "))
x = ''

while working !=0:
    remainder = working % 2
    working = working // 2

    if remainder == 0:
        x += '0'
        print (working, x)

    else:
        x += '1'
        print (working, x)

print ("I believe your binary number is " , x[::-1])

Note how x is initially declared as an empty string '' instead of the empty tuple (). This makes it so that when you use the += operator later to append 0 or 1 to it, that it is treated as string concatenation instead of addition.

It should be

working = int(input("Please select a non-negative decimal number to convert to binary.  "))
x = ""

while working !=0:
    remainder = working % 2
    working = working // 2

    if remainder == 0:
      x = x + str(remainder)
      print (working, x)

    else:
     x = x + str(remainder)
    print (working, x)

print ("I believe your binary number is " ,x[::-1])

Change your code to below:

if remainder == 0:
    x = str(remainder) + '0'
    print (working, x)

else:
    x = str(remainder) + '1'
    print (working, x)

in your code, python interprets as an int you have to cast it to string.

another way is using built-in function bin(working), directly converts from number to binary value.