Python check string pattern follows xxxx-yyyy-zzzz

Question

I am trying to build a check for strings that allows a pattern "xxxx-yyyy-zzzz". The string needs to have three blocks seperated by "-". Each block can contain "a-z", "A-Z", "_" (underscore) and "." (dot).

This is what I got to now:

file_name: str = "actors-zero-This_Is_Fine.exe.yml"
ab = re.compile("^([A-Z][0-9])-([A-Z][0-9])-([A-Z][0-9])+$")
if ab.match(file_name):
    pass
else:
    print(f"WARNING wrong syntax in {file_name}")
    sys.exit()

Output is:

WARNING wrong name in actors-zero-This_Is_Fine.exe.yml

Asked By: Europa

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Source

Answer 1

What exactly is your question?
This looks alright so far. Your file name returns the warning because you have not specified the underscores in the third "block".

Instead of ([A-Z][0-9]). you could use character classes:

Like so: ^([w.]+)-([w.]+)-([w.]+)$

Generally, I found the chapter in Automate The Boring Stuff on regex Pattern matching very concise and helpful:
https://automatetheboringstuff.com/2e/chapter7/
You will find the above table in this chapter also.

Answered By: ChriSil

Answer 2

If I understand the question correctly, you want 3 groups of alphanumerical characters (plus .) separated by dashes:
Regex for this would be ^([w.]+)-([w.]+)-([w.]+)$

^ matches the start of a string
Then we have 3 repeating groups:
([w.]+) will match letters, numbers, underscores (w) and dots (.) at least one time (+)
We make 3 of these, then separate each with a dash.

We finish off the regex with a $ to match the end of the string, making sure you’re matching the whole thing.

Answered By: Adid

Python check string pattern follows xxxx-yyyy-zzzz

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