如何在Python中用零填充数字字符串？

Python strings have a method called zfill that allows to pad a numeric string with zeros to the left.

Python字符串有一个名为zfill的方法，它允许用左边的零填充数字字符串。

In : str(190).zfill(8)
Out: '00000190'

How can I make the pad to be on the right ?

如何让垫子在右边？

3 个解决方案

#1

See Format Specification Mini-Language:

请参阅格式规范迷你语言：

In [1]: '{:<08d}'.format(190)
Out[1]: '19000000'

In [2]: '{:>08d}'.format(190)
Out[2]: '00000190'

#2

Hint: The string can be inverted twice: before and after using the zfill method:

提示：字符串可以反转两次：使用zfill方法之前和之后：

In : acc = '991000'

In : acc[::-1].zfill(9)[::-1]
Out: '991000000'

Or even more easier:

或者更容易：

In : acc.ljust(9, '0')
Out: '991000000'

#3

As maybe a alternative more portable [1] and efficient [2], actually you can just use str.ljust.

作为替代更便携[1]和高效[2]的替代方案，实际上你可以使用str.ljust。

In [2]: '190'.ljust(8, '0')
Out[2]: '19000000'

In [3]: str.ljust?
Docstring:
S.ljust(width[, fillchar]) -> str

Return S left-justified in a Unicode string of length width. Padding is
done using the specified fill character (default is a space).
Type:      method_descriptor

[1] format is not present on old python versions. format specifier was added since Python 3.0 (see PEP 3101) and Python 2.6.

[1]格式在旧的python版本中不存在。格式说明符是从Python 3.0（参见PEP 3101）和Python 2.6开始添加的。

[2] reverse twice is an expensive operation.

[2]反转两次是一项昂贵的操作。

#1