您可以在一组字符后放置一个 ? 以使其可选.

You can put a ? after a group of characters to make it optional.

您想要一个点后跟任意数量的数字 \.\d+，组合在一起 (\.\d+)，可选 (\.\d+)?.坚持你的模式:

You want a dot followed by any number of digits \.\d+, grouped together (\.\d+), optionally (\.\d+)?. Stick that in your pattern:

import re
print re.match("(\d+(\.\d+)?)", "3434.35353").group(1)

3434.35353

print re.match("(\d+(\.\d+)?)", "3434").group(1)

3434