CODEWITHSUNDEEP
pythonregex
dahiya_boy
dahiya_boy

Reputation: 9503

Regex not giving proper result in python

I have to search string with format aaa.aaa.aaa. ...... n times, "a" can be any alphanumeric or special char.

For the pattern I made ^.{3}(\..{3})* regex

^.{3} => Starting first 3 chars can be any

(\..{3})* => Next should be dot and followed by 3 any chars ntimes (0 or more times repetitions)

The issue is regex pattern returns true if it matches first 3 chars and it ignores the optional condition. Is there any way to resolve the issue?

Regex101: https://regex101.com/r/KpI9VF/2

Python Code:

import re
import sys

regex_pattern = r"^.{3}(?:\..{3})*"

test_array = ["123.456.abc.def",
              "1123.456.abc.def",
              "123.125.528.256",
              "asd.asd.asd.asd",
              "123456789.2.2.2",
              "123.125.528.256",
              "123456789.2.2.2",
              "...............",
              "...",
              "`!@.#$%.^&*.()_",
              "1234.123.123.123",
              "123.123.123.1234",
              "...123.123.123.123..."
             ]

for test_string in test_array:
  match_res = re.match(regex_pattern, test_string) is not None
  print(test_string + " ==> " +str(match_res).lower())

Output:

123.456.abc.def ==> true
1123.456.abc.def ==> true
123.125.528.256 ==> true
asd.asd.asd.asd ==> true
123456789.2.2.2 ==> true
123.125.528.256 ==> true
123456789.2.2.2 ==> true
............... ==> true
... ==> true
`!@.#$%.^&*.()_ ==> true
1234.123.123.123 ==> true
123.123.123.1234 ==> true
...123.123.123.123... ==> true

Expected Output

123.456.abc.def     true
1123.456.abc.def    false
123.125.528.256     true
asd.asd.asd.asd     true
123456789.2.2.2     false
123.125.528.256     true
123456789.2.2.2     false
...............     true
...         false
`!@.#$%.^&*.()_     true
1234.123.123.123    false
123.123.123.1234    false
...123.123.123.123...   false

Upvotes: 0

Views: 126

Answers (2)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627536

You can use

^.{3}(?:\..{3})+$

See the regex demo.

Details:

  • ^ - start of string
  • .{3} - any 3 chars other than line break chars
  • (?:\..{3})+ - one or more occurrences of
    • \. - a . char
    • .{3} - any 3 chars other than line break chars
  • $ - end of string.

See the regex graph:

enter image description here

Upvotes: 2

nizarcan
nizarcan

Reputation: 535

By the definition you gave in the question, ... should match with the pattern. And what you also need is a string ending anchor $.

I believe if you update your expression as r"^.{3}(\..{3})*$"(Also removed ?:), it works as intended.

Upvotes: 1

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