I want to create a shortcut ctrl+c to toggle comment for .vhd files, so thing should be like this:
when I press Ctrl+c, in vim normal mode, it should add "-- " at the begining of the actual line.
I tried to add "nmap < C-c > <--space> " in my vimrc file,but it didn't work.
You probably want to use a plugin like vim-commentary
That said, you can achieve what you want with the following mapping:
nmap <C-c> I-- <esc>