sanitize_user filter-hook . WP 2.0.1

Filters a sanitized username string.

Usage

add_filter( 'sanitize_user', 'filter_function_name_2777', 10, 3 );
function filter_function_name_2777( $username, $raw_username, $strict ){
	// filter...

	return $username;
}

$username(string)

Sanitized username.

$raw_username(string)

The username prior to sanitization.

$strict(true/false)

Whether to limit the sanitization to specific characters.
Default: false

Where the hook is called

return apply_filters( 'sanitize_user', $username, $raw_username, $strict );

Where the hook is used (in WP core)

add_filter( 'sanitize_user', 'strtolower' );