in htaccess redirect code example

Example 1: redirect htaccess non www to www

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ http://www.%{HTTP_HOST}/$1 [R=301,L]

Example 2: htacces redirect

RewriteEngine On
RewriteCond %{HTTP_HOST} !^www\.vecchiodominio\.com$
RewriteRule (.*) http://www.nuovodominio.com/$1 [R=301,L]
RewriteCond %{HTTP_HOST} !^vecchiodominio\.com$
RewriteRule (.*) http://www.nuovodominio.com/$1 [R=301,L]