Remove trailing zeros from binary result in python

Question

We have a program that changes decimals to binary.
And the goal is to run the program, input a value, and outputs the value in binary.

The problem with my code is that it has trailing zeros when outputting the binary.
I need to achieve this without using external libraries like "math", so please stick to the built-in functions.

Current output:

Insert a value:
5
The number fits in 1 byte and is in binary:
00000101
Insert a value:
100
The number fits in 1 byte and is in binary:
01100100
Insert a value:
280
The number fits in 16 bits and is in binary:
0000000100011000

Expected output:

Insert a value:
5
The number fits in 1 byte and is in binary:
101
Insert a value:
100
The number fits in 1 byte and is in binary:
1100100
Insert a value:
280
The number fits in 16 bits and is in binary:
100011000

Current code:

def dec2bin(value, number_bits):
    result = ''
    while number_bits > 0:
        bit_value = 2 ** (number_bits - 1)
        if value >= bit_value:
            result = result + '1'
            value = value - bit_value
        else:
            result = result + '0'
        number_bits = number_bits - 1
    print(result)

input_ok = False
userinput = 0
while not input_ok:
    print('Insert a value:')
    userinput = int(input())
    if userinput > 65535:
        print('invalid, cant handle that big numbers, try again')
    else:
        input_ok = True
    if userinput < 256:
        print('The number fits in 1 byte and is in binary:')
        dec2bin(userinput, 8)
    else:
        print('The number fits in 16 bits and is in binary:')
        dec2bin(userinput, 16)

Does this answer your question? [How to remove leading and trailing zeros in a string? Python](https://stackoverflow.com/questions/13142347/how-to-remove-leading-and-trailing-zeros-in-a-string-python) — Pranav Hosangadi, Jul 14 '21 at 19:39

score 1 · Accepted Answer · answered Jul 14 '21 at 19:49

It easy with string formatting functions (see Pranav's comment). But perhaps in this case you want the algorithm to take care of it, and see treating it as a string is cheating.

def dec2bin(value, number_bits):
    result = ''
    starting = True
    while number_bits > 0:
        bit_value = 2 ** (number_bits - 1)
        if value >= bit_value:
            result = result + '1'
            value = value - bit_value
            starting = False
        elif not starting:
            result = result + '0'
        number_bits = number_bits - 1
    print(result)

score 1 · Answer 2 · answered Jul 14 '21 at 19:56

1

Since you are storing the value as a string you can use

result.lstrip('0')

to remove the leading zeros from your answer.

answered Jul 14 '21 at 19:56

0x263A

1,807
9
22

@kabax this is in the accepted answer in my linked duplicate. Please read linked questions / answers carefully. [How much research effort is expected of Stack Overflow users?](//meta.stackoverflow.com/a/261593/843953) – Pranav Hosangadi Jul 14 '21 at 22:35

Remove trailing zeros from binary result in python

2 Answers2