关于分组优先以及 " | " 的细致练习
from django.test import TestCase import re # Create your tests here. ret = re.findall(r"-?\d+\.\d*|-?\d+", "1-2*(60+(-40.35/5)-(-4*3))") print(ret) # ['1', '-2', '60', '-40.35', '5', '-4', '3'] ret = re.findall(r"-?\d+\.\d*|(-?\d+)", "1-2*(60+(-40.35/5)-(-4*3))") print(ret) # ['1', '-2', '60', '', '5', '-4', '3'] ret = re.findall(r"-?\d+|-?\d+\.\d*", "1-2*(60+(-40.35/5)-(-4*3))") print(ret) # ['1', '-2', '60', '-40', '35', '5', '-4', '3'] ret = re.findall(r"-?\d+|(-?\d+\.\d*)", "1-2*(60+(-40.35/5)-(-4*3))") print(ret) # ['', '', '', '', '', '', '', ''] ret = re.findall(r"(-?\d+\.\d*)|-?\d+", "1-2*(60+(-40.35/5)-(-4*3))") print(ret) # ['', '', '', '-40.35', '', '', '']
"|" 的匹配顺序从左向右 , 而且一旦匹配上了就不会匹配后面的那段正则
"()" 是将被匹配的优先显示, 但是匹配不中的内容会被用 "" 空字符串来表示