如何检查字符串是否仅包含 python 中的特定字符？

Question

I want my string only have (a-zA-Z0-9@.-_) but when using this code:

import re
e='p12/5@gmail.com'
p=re.compile(r'[a-zA-Z0-9@.-_]')
for ele in e:
    if bool(p.search(ele)):
        print('okay')
    else:
        print('n')

it prints 'okay' but I expect to print 'n' because my string(e) contains '/' and I didn't declare it on my regex. what should I do? I also used re.match and didn't help me either.

Answer 1

There are a couple of issues here. First . and - are meta-characters, and need to escaped with a \ . Second, you don't really need the loop here - add a * to indicate any number of these characters, and qualify the regex between ^ and $ to signify the entire string needs to be made up of these characters:

import re
e = 'p12/5@gmail.com'
p = re.compile(r'^[a-zA-Z0-9@\.\-_]*$')

if p.match(e):
    print('okay')
else:
    print('n')