I work on a linux computer (emacs26) without internet,usb,share ...
developing C program,
no way to install auto-complete/company-mode/lsp,

when I edit my init.el, (setq var-xx-, no auto completion, painfull,
any package can complete elisp variable/function like auto-complete-mode ?

For c programming, I only have cscope, but also no function/var completion,
there is cedet, I will try to configure it.