PHP Benutzername Regex
/^[a-z0-9][a-z0-9_]{2,28}[a-z0-9]$/i
Condemned Cassowary
/^[a-z0-9][a-z0-9_]{2,28}[a-z0-9]$/i^(?=\P{Ll}*\p{Ll})(?=\P{Lu}*\p{Lu})(?=\P{N}*\p{N})(?=[\p{L}\p{N}]*[^\p{L}\p{N}])[\s\S]{8,}$