I am using same expression for .net application and javascript it is working fine but when I used for boost regular expression the following problem is facing But it is failed to validate foramt like 2001:470:1f01:115::1 or 2001::11 or 2001:1::11 Please see my code... bool IsValidIPv6String(wstring ipv6address) { wsmatch what; wregex expression(L"^((([0-9A-Fa-f]{1,4}:){7}[0-9A-Fa-f]{1,4})|(([0-9A-Fa-f]{1, 4}:){6}:[0-9A-Fa-f]{1,4})|(([0-9A-Fa-f]{1,4}:){5}:([0-9A-Fa-f]{1,4}:)?[0 -9A-Fa-f]{1,4})|(([0-9A-Fa-f]{1,4}:){4}:([0-9A-Fa-f]{1,4}:){0,2}[0-9A-Fa -f]{1,4})|(([0-9A-Fa-f]{1,4}:){3}:([0-9A-Fa-f]{1,4}:){0,3}[0-9A-Fa-f]{1, 4})|(([0-9A-Fa-f]{1,4}:){2}:([0-9A-Fa-f]{1,4}:){0,4}[0-9A-Fa-f]{1,4})|(( [0-9A-Fa-f]{1,4}:){6}((\\b((25[0-5])|(1\\d{2})|(2[0-4]\\d)|(\\d{1,2}))\\ b)\\.){3}(\\b((25[0-5])|(1\\d{2})|(2[0-4]\\d)|(\\d{1,2}))\\b))|(([0-9A-F a-f]{1,4}:){0,5}:((\\b((25[0-5])|(1\\d{2})|(2[0-4]\\d)|(\\d{1,2}))\\b)\\ .){3}(\\b((25[0-5])|(1\\d{2})|(2[0-4]\\d)|(\\d{1,2}))\\b))|(::([0-9A-Fa- f]{1,4}:){0,5}((\\b((25[0-5])|(1\\d{2})|(2[0-4]\\d)|(\\d{1,2}))\\b)\\.){ 3}(\\b((25[0-5])|(1\\d{2})|(2[0-4]\\d)|(\\d{1,2}))\\b))|(([0-9A-Fa-f]{1, 4}:){0,5}::([0-9A-Fa-f]{1,4}:){0,5}[0-9A-Fa-f]{1,4})|(::([0-9A-Fa-f]{1,4 }:){0,6}[0-9A-Fa-f]{1,4})|(([0-9A-Fa-f]{1,4}:){1,7}:))$"); Please look into the expression. Regards Gopal