相关疑难解决方法(0)

在这个python示例之后,我将字符串编码为Base64,其中:

>>> import base64
>>> encoded = base64.b64encode(b'data to be encoded')
>>> encoded
b'ZGF0YSB0byBiZSBlbmNvZGVk'

但是,如果我省略领先b:

>>> encoded = base64.b64encode('data to be encoded')

我收到以下错误:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python32\lib\base64.py", line 56, in b64encode
   raise TypeError("expected bytes, not %s" % s.__class__.__name__)
   TypeError: expected bytes, not str

为什么是这样？