Tutorial Redirect non www url's to www / vice versa in 4 different ways

Rewritecond %{http_host} ^phcorner.net [nc]
Rewriterule ^(.*)$ https://phcorner.net/$1 [r=301,nc]

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

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

RewriteCond %{HTTP_HOST} ^phcorner.net [NC]
RewriteRule ^(.*)$ https://phcorner.net/$1 [L,R=301]

Rewritecond %{https_host} ^phcorner.net [nc]
Rewriterule ^(.*)$ https://phcorner.net/$1 [r=301,nc]

RewriteCond %{https_HOST} !^www\.phcorner\.net$
RewriteRule (.*) https://phcorner.net/$1 [R=301,L]

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

RewriteCond %{https_HOST} ^phcorner.net [NC]
RewriteRule ^(.*)$ https://phcorner.net/$1 [L,R=301]