测试正则表达式是否匹配
Enter your regex: <(BR|br)\/?>
Enter input string to search: test <br>test
Found "<br>" starting index 5 ending index 9.
Enter your regex: <(BR|br)\/?>
Enter input string to search: test <BR/
No match found.
Enter your regex: <(BR|br)\/?>
Enter input string to search: test <BR/>
Found "<BR/>" starting index 6 ending index 11.
