Clean and Normalize DOI Strings

Strips common URL prefixes (including bare 'doi.org/'), leading/trailing whitespace, and verifies that the resulting string follows standard DOI format.

Usage

clean_doi_string(raw_doi)

Arguments

raw_doi

Character string containing a raw DOI or DOI URL.

Value

Character string containing the clean DOI (e.g., "10.1579/..."), or NULL if input is invalid or missing the '10.' prefix.