What does 'h' mean in a python format string?

问题

This is a valid python format string:

>>> wierd_format = '[%27he]'
>>> print wierd_format % 2.5
[        2.500000e+00]

But this isn't:

>>> bad_format = '[%20qe]'
>>> print bad_format % 2.5
Traceback (most recent call last):
  File "prog.py", line 5, in <module>
    print bad_format % 2.5
ValueError: unsupported format character 'q' (0x71) at index 4

Clearly, h is a supported format character. However, the documentation doesn't mention an h specifier. What does it do?

回答1:

From the docs:

A length modifier (h, l, or L) may be present, but is ignored as it is not necessary for Python – so e.g. %ld is identical to %d.

回答2:

Python Docs say that it is a length modifier.

A length modifier (h, l, or L) may be present, but is ignored as it is not necessary for Python. so e.g. %ld is identical to %d.

They seem the same,

>>> "[%he]" %2.5
'[2.500000e+00]'
>>> "[%le]" %2.5
'[2.500000e+00]'
>>> "[%Le]" %2.5
'[2.500000e+00]'

来源：https://stackoverflow.com/questions/18174827/what-does-h-mean-in-a-python-format-string