Python - 显式匹配字符串中的字符串

Question

I am trying to match specific router interfaces. However, I am finding the below confusing, when searching for specific interface numbers, it is matching on the first condition, when i think it should be matching on the second condition:

string = ["TenGigE0/0/0/0.12", "TenGigE0/0/0/1.46", "TenGigE0/0/0/15.55"]

for item in string:
    if 'TenGigE0/0/0/0' in item or 'TenGigE0/0/0/1' in item:
        print("Yes")
    elif 'TenGigE0/0/0/15' in item:
        print("cool")

Output is:

Yes
Yes
Yes

How can i fix this?

Answer 1

Change the if-statements around:

string = ["TenGigE0/0/0/0.12", "TenGigE0/0/0/1.46", "TenGigE0/0/0/15.55"]

for item in string:
    if 'TenGigE0/0/0/15' in item:
        print("cool")
    elif ('TenGigE0/0/0/0' in item) or ('TenGigE0/0/0/1' in item):
        print("Yes")

Will get you:

Yes
Yes
cool

Since TenGigE0/0/0/15 contains TenGigE0/0/0/1 too, and if you check for TenGigE0/0/0/1 before checking for TenGigE0/0/0/15 the first if-statement results in True

Answer 2

Let's visualise this:

• 'TenGigE0/0/0/0' in 'TenGigE0/0/0/0.12' is true, because 'TenGigE0/0/0/0' is a substring of 'TenGigE0/0/0/0.12' :

   TenGigE0/0/0/0.12 TenGigE0/0/0/0

• 'TenGigE0/0/0/1' in 'TenGigE0/0/0/1.46' is true, because 'TenGigE0/0/0/1' is a substring of 'TenGigE0/0/0/1.46' :

   TenGigE0/0/0/1.46 TenGigE0/0/0/1

• Same for 'TenGigE0/0/0/15.55' :

   TenGigE0/0/0/15.55 TenGigE0/0/0/1

if statement executes the code after the first condition that is True , so even though 'TenGigE0/0/0/15' in 'TenGigE0/0/0/15.55' is True, 'TenGigE0/0/0/1' in 'TenGigE0/0/0/15.55' was first , so that's what got executed.

Answer 3

As already mentioned in other answers, '/1' is a substring of '/15' .

Another solution is to use regex with a word bound \b and a group for '0' OR '1' :

import re

string = ["TenGigE0/0/0/0.12", "TenGigE0/0/0/1.46", "TenGigE0/0/0/15.55"]
for item in string:
    if re.match(r'TenGigE0/0/0/(0|1)\b', item):
        print("Yes")
    elif re.match(r'TenGigE0/0/0/15\b', item):
        print("cool")

Output:

Yes
Yes
cool