python字符串格式及填充

在字符串前填充0到指定长度

>>> n = '4'
>>> print(n.zfill(3))
  004

1. format

   >>> n = 4
   >>> print('%03d' % n)
   004
   >>> print(format(n, '03')) # python >= 2.6
   004
   >>> print('{0:03d}'.format(n))  # python >= 2.6
   004
   >>> print('{foo:03d}'.format(foo=n))  # python >= 2.6
   004
   >>> print('{:03d}'.format(n))  # python >= 2.7 + python3
   004
   >>> print('{0:03d}'.format(n))  # python 3
   004
   >>> print(f'{n:03}') # python >= 3.6
   004
   

2.rjust/ljust 左对齐 右对齐

>>> '99'.rjust(5,'0')
'00099'

千分割符，适合python3.x

‘{:,}’.format(1234567890)
‘1,234,567,890’