Quoting: ColomboCan you suggest me lightweight IDE that has that whispering and documentation? (and autocompletion)?

Atom (https://atom.io/) is very clean and lightweight, and supports quite a lot of features through extensions.

Sublime Text 3 works great for me.

I use IntelliJ IDEA for all my Java work and I wouldn't change it for any other IDE.

I'm using (if I find time and motivation after programming on Windows at work) Eclipse CDT.

Netbeans is my favorite, definitely. I just have to add a GTK UI configuration to make it looks nice and it make it alot better

Wow.... surprised nobody has mentioned Codelite.

I've used just about every text editor & IDE out there, Codelite is what I've stuck with.

For quick or small projects I tend to use Nano with tmux + other crap. Other times I use Atom.io

xed, make, and gcc

I use vim too on a daily basis. I'm surprised so few people here use it.

I used to work with Eclipse, but it felt heavy and getting slower with each update. At work we have a special version of micro emacs, which still is an IDE, as you can compile your C programs from it and jump into the code when having errors.
For minor changes on text files, I just use vim... but meanwhile my favorite editor is Sublime Text 3.
I've found a video tutorial online, called Perfect Workflow with Sublime Text, and that showed my how awesome Sublime Text is.
Meanwhile Atom.io might be also quite similar, or even Microsoft's Visual Code... but I still stick with Sublime Text, as I payed the license fee (imho it's totally worth it) and got so used to it, that I don't want to have any other editor again.
It lacks some features big IDEs have, but I can get along with that.