Python Regex is not working for the given pattern

Question

I'm trying to extract a pattern from string using python regex. But it is not working with the below pattern

headerRegex = re.compile(r'^[^ ]*\s+\d*') 
        mo = headerRegex.search(string) 
        return mo.group()

My requirment is regular expression that should start with anything except white space and followed by one or more whitespace then digits occurence one or more

Example
i/p: test  7895  => olp:7895(correct)
i/p:  8545 ==> Not matching
i/p: @#@#  3453 ==>3453

May I know what is missing in my regex to implement this requirement?

Answer 1

In the pattern that you tried, only matching whitespace chars is mandatory, and you might possibly also match only newlines.

Change the quantifiers to + to match 1+ times, and if you don't want to match newlines as well use [^\S\r\n]+ instead.

If that exact match is only allowed, add an anchor $ to assert the end of the string, or add \Z if there is no newline following allowed.

^\S+[^\S\r\n]+\d+$

• ^ Start of string
• \S+ Match 1+ times a non whitespace char
• [^\S\r\n]+ Match 1+ times a whitespace char except newlines
• \d+ Match 1+ digits
• $ End of string

Regex demo