正则表达式 re.findall 用法

正则 re.findall 的简单用法（返回string中所有与pattern相匹配的全部字串，返回形式为数组）

语法：

findall(pattern, string, flags=0)

import re
Python 正则表达式 re findall 方法能够以列表的形式返回能匹配的子串

print (help(re.findall))
print (dir(re.findall))

findall查找全部r标识代表后面是正则的语句

regular_v1 = re.findall(r"docs",“https://docs.python.org/3/whatsnew/3.6.html”)
print (regular_v1)
[‘docs’]

符号^表示匹配以https开头的的字符串返回,

 regular_v2 = re.findall(r"^https","https://docs.python.org/3/whatsnew/3.6.html")print (regular_v2)['https']

用$符号表示以html结尾的字符串返回,判断是否字符串结束的字符串

regular_v3 = re.findall(r"html$","https://docs.python.org/3/whatsnew/3.6.html")
print (regular_v3)
['html']

[…]匹配括号中的其中一个字符

regular_v4 = re.findall(r"[t,w]h","https://docs.python.org/3/whatsnew/3.6.html")
print (regular_v4)['th', 'wh']

“d”是正则语法规则用来匹配0到9之间的数返回列表

regular_v5 = re.findall(r"\d","https://docs.python.org/3/whatsnew/3.6.html")
regular_v6 = re.findall(r"\d\d\d","https://docs.python.org/3/whatsnew/3.6.html/1234")
print (regular_v5)
['3', '3', '6']
print (regular_v6)
['123']

小d表示取数字0-9，大D表示不要数字，也就是出了数字以外的内容返回

regular_v7 = re.findall(r"\D",“https://docs.python.org/3/whatsnew/3.6.html”)
print (regular_v7)
[‘h’, ‘t’, ‘t’, ‘p’, ‘s’, ‘:’, ‘/’, ‘/’, ‘d’, ‘o’, ‘c’, ‘s’, ‘.’, ‘p’, ‘y’, ‘t’, ‘h’, ‘o’, ‘n’, ‘.’, ‘o’, ‘r’, ‘g’, ‘/’, ‘/’, ‘w’, ‘h’, ‘a’, ‘t’, ‘s’, ‘n’, ‘e’, ‘w’, ‘/’, ‘.’, ‘.’, ‘h’, ‘t’, ‘m’, ‘l’]

“w”在正则里面代表匹配从小写a到z,大写A到Z，数字0到9

regular_v8 = re.findall(r"\w","https://docs.python.org/3/whatsnew/3.6.html")
print (regular_v8)
['h', 't', 't', 'p', 's', 'd', 'o', 'c', 's', 'p', 'y', 't', 'h', 'o', 'n', 'o', 'r', 'g', '3', 'w', 'h', 'a', 't', 's', 'n', 'e', 'w', '3', '6', 'h', 't', 'm', 'l']

“W”在正则里面代表匹配除了字母与数字以外的特殊符号

regular_v9 = re.findall(r"\W","https://docs.python.org/3/whatsnew/3.6.html")
print (regular_v9)
[':', '/', '/', '.', '.', '/', '/', '/', '.', '.']