bytes

class bytes(object):
    """
    bytes(iterable_of_ints) -> bytes
    bytes(string, encoding[, errors]) -> bytes
    bytes(bytes_or_buffer) -> immutable copy of bytes_or_buffer
    bytes(int) -> bytes object of size given by the parameter initialized with null bytes
    bytes() -> empty bytes object

    Construct an immutable array of bytes from:
      - an iterable yielding integers in range(256)
      - a text string encoded using the specified encoding
      - any object implementing the buffer API.
      - an integer
    """

Python中的字节码用b‘xxx‘的形式表示。x可以用字符表示，也可以用ASCII编码形式\xnn表示，nn从00-ff(十六进制)共256种字符。　

a = ‘abc‘
b = bytes(a, ‘utf-8‘)
print(b)
c = bytes(a, ‘gbk‘)
print(c)
# 结果 b‘abc‘
# 结果 b‘abc‘

a = ‘你好‘
b = bytes(a, ‘utf-8‘)
print(b)
c = bytes(a, ‘gbk‘)
print(c)
# 结果 b‘\xe4\xbd\xa0\xe5\xa5\xbd‘
# 结果 b‘\xc4\xe3\xba\xc3‘

decode

c = bytes(a, ‘gbk‘).decode(‘gbk‘)
print(c)
# 结果 你好