import re
regex = re.compile(r"^(?:(?:[A-Za-z][A-Za-z0-9.-]*@(?:aig\.com|abc\.in|abc\.uk))(?:,(?!$)|$))*$", flags=re.MULTILINE)
test_str = ("abc@aig.com\n"
"abc@aig.com,xyz@abc.uk\n"
"abc@aig.com,\n"
"abc@aig.com,xyz@abc.uk,\n"
"xyz@aig.com,@xyz@abc.in,xyz@abc.uk\n"
"xyz@aig.com,xyz@abc.in,xyz@abc.uk\n"
"xyz@aig.com,xyz@abc.in,xyz@abc.com")
matches = regex.finditer(test_str)
for match_num, match in enumerate(matches, start=1):
print(f"Match {match_num} was found at {match.start()}-{match.end()}: {match.group()}")
for group_num, group in enumerate(match.groups(), start=1):
print(f"Group {group_num} found at {match.start(group_num)}-{match.end(group_num)}: {group}")
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Python, please visit: https://docs.python.org/3/library/re.html