To redirect http:// or https:// to https://www you can use the following rule on all versions of apache :
RewriteEngine on
RewriteCond %{HTTPS} off [OR]
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^ https://www.example.com%{REQUEST_URI} [NE,L,R]
Apache 2.4
RewriteEngine on
RewriteCond %{REQUEST_SCHEME} http [OR]
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^ https://www.example.com%{REQUEST_URI} [NE,L,R]
Note that The %{REQUEST_SCHEME} variable is available for use since apache 2.4 .