Man pages matching name fopen in section 3:

fopen.3.de	debian 10 / manpages-de-dev
fopen.3.en	debian 10 / manpages-dev
fopen.3.es	debian 10 / manpages-es
fopen.3.ja	debian 10 / manpages-ja-dev
fopen.3.pl	debian 10 / manpages-pl-dev
fopen.3.pt	debian 10 / manpages-pt-dev
fopen.3.zh_CN	debian 10 / manpages-zh
fopen.3.zh_TW	debian 10 / manpages-zh
fopen.3.de	debian 11 / manpages-de-dev
fopen.3.en	debian 11 / manpages-dev
fopen.3.es	debian 11 / manpages-es-dev
fopen.3.ja	debian 11 / manpages-ja-dev
fopen.3.pl	debian 11 / manpages-pl-dev
fopen.3.pt	debian 11 / manpages-pt-dev
fopen.3.zh_CN	debian 11 / manpages-zh
fopen.3.zh_TW	debian 11 / manpages-zh
fopen.3.de	debian 12 / manpages-de-dev
fopen.3.en	debian 12 / manpages-dev
fopen.3.fr	debian 12 / manpages-fr-dev
fopen.3.ja	debian 12 / manpages-ja-dev
fopen.3.ru	debian 12 / manpages-ru-dev
fopen.3.zh_CN	debian 12 / manpages-zh
fopen.3.zh_TW	debian 12 / manpages-zh