Python：如何向二进制字符串添加可变长度前导零？

Question

我希望向 my_string = '01001010' 添加前导零，以确保至少有 'length' 位字符串，其中 length >= len(my_string)

Answer 1

我定义了一个函数，它将未知基数的整数（十六进制、十进制、八进制、二进制等）转换为位。这些位用零填充到用户定义的最小长度，并在必要时溢出到额外的位，而不填充零。

def convert_bits(obj, **kwargs):

    if 'base' in kwargs:

        base = int(kwargs.get('base'))

    else:

        base = 10

    if 'location' in kwargs:

        location = int(kwargs.get('location'))

    else:

        location = -1

    if 'subroutine' in kwargs:

        subroutine = str(kwargs.get('subroutine'))

    else:

        subroutine = ''

    try:

        if 'length' in kwargs:

            length = int(kwargs.get('length'))

            bitstream = "{0:0{1:}b}".format(int(str(obj), base), length)           

            if len(bitstream) != length:

                raise OverflowException(

                     bitstream=bitstream, length=length, location=location, 

subroutine=subroutine)

        else:

            bitstream = "{0:0b}".format(int(str(obj), base))

    except Exception as e:

        print(f"Exception in convert_bits method: {e}\n")

    return bitstream

class OverflowException(Exception):

def __init__(self, **kwargs):

    if kwargs:

        try:

            self.length = int(kwargs.get('length'))

            self.bitstream = str(kwargs.get('bitstream'))

            self.location = int(kwargs.get('location'))

            self.subroutine = str(kwargs.get('subroutine'))

        except:

            print('exception intializing OverflowException\n')

            self.length = 0

            self.bitstream = ''

def __str__(self):

    if self.bitstream and self.length:

        if self.subroutine and self.location is not None:

            return f"OVERFLOW! Bitstream has {len(self.bitstream)} bits, exceeding {self.length} at index:{self.location} in {self.subroutine}"

        else:

            print('No location / subroutine found!\n')

            return f"OVERFLOW! Bitstream has {len(self.bitstream)} bits, exceeding {self.length}"

    else:

        return f"OVERFLOW!"