Python中是否存在负正则表达式（否定）？

Question

Let's say that I want to make a RE that describes all integers. By definition the expression is:

(+|-)?[0-9]+

But the definition also matches these numbers : +0, -0, 0045

The 0045 occasion can probably be solved using a lookback expression but how can I excusively exclude the +0 and -0 strings from the RE. I thought the syntax for this was ^(+0|-0 ) but that's probably a RE syntax for an other framework not Pythons'.

Answer 1

Then the case of zero can be handled separately. Regular expression for zero or non-zero numbers:

0|[+-]?[1-9][0-9]*

The assumptions were:

• no superfluous heading zeroes.
• no sign before zero
• superfluous plus sign allowed before non-zero numbers.

Outside a character group (with square brackets), the symbol ^ means the start of the string or line depending on the flag setting of re.MULTILINE .