如何在python中获得作为动态输入的重模式？

我在python中使用re模块进行一些正则表达式操作。当我在python程序中定义了静态匹配的模式时，它工作得很好

比如说,

import re
s="hi can you help me out"
pattern=r'[a-z ]*' #pattern that takes space and lower case letters only
i= re.fullmatch(pattern,s) #to check the entire string
print(i.string)


output:
hi can you help me out

现在让我来谈谈我所面临的问题，如果我试图在运行时从用户那里获取输入模式，它会抛出异常

import re
s="hi can you help me out"
pattern=input("Enter pattern:")
i= re.fullmatch(pattern,s)
print(i.string)

output:
Enter pattern:r'[a-z]*'
Exception has occurred: AttributeError
'NoneType' object has no attribute 'string'

希望有人能帮我解决这个问题

python版本：3.5

---

提前感谢

您只需输入此部分

[a-z]*

，不带

r

字符串前缀：

Python 3.x：

import re
s = "hi can you help me out"
pattern = input("Enter pattern:")
i = re.fullmatch(pattern,s)
print(i.string)

import re
s = "hi can you help me out"
pattern = raw_input("Enter pattern:")   # since input() in python2.x is the same eval(raw_input()) which would return an int
i = re.fullmatch(pattern,s)
print(i.string)

Enter pattern:[a-z ]*
hi can you help me out

Python 2.x：

import re
s = "hi can you help me out"
pattern = input("Enter pattern:")
i = re.fullmatch(pattern,s)
print(i.string)

import re
s = "hi can you help me out"
pattern = raw_input("Enter pattern:")   # since input() in python2.x is the same eval(raw_input()) which would return an int
i = re.fullmatch(pattern,s)
print(i.string)

Enter pattern:[a-z ]*
hi can you help me out

输出：

import re
s = "hi can you help me out"
pattern = input("Enter pattern:")
i = re.fullmatch(pattern,s)
print(i.string)

import re
s = "hi can you help me out"
pattern = raw_input("Enter pattern:")   # since input() in python2.x is the same eval(raw_input()) which would return an int
i = re.fullmatch(pattern,s)
print(i.string)

Enter pattern:[a-z ]*
hi can you help me out

---

你参加什么？适用于

Enter模式：[a-z]*

PS。请注意

r'

开头

r'

和结尾

'

不是模式的一部分，因为您输入了

r'[a-z]*

作为输入，而不是

[a-z]*

@GomathiMeena您是否正在使用Python 2.x？@GomathiMeena显示错误