How to force redirection (or not) to www.example.com in .htacces

in .htacces we can force redirection to http://www.yourdomain.com by using these lines:

# rewrite example.com → www.example.com
RewriteEngine On
RewriteCond %{HTTP_HOST} !^$
RewriteCond %{HTTP_HOST} !^www\. [NC]
RewriteCond %{HTTPS}s ^on(s)|
RewriteRule ^ http%1://www.%{HTTP_HOST}%{REQUEST_URI} [R=301,L]

or we can force not to use www by using these lines:

# rewrite www.example.com → example.com

<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteCond %{HTTPS} !=on
    RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
    RewriteRule ^ http://%1%{REQUEST_URI} [R=301,L]
</IfModule>