Universal Feature

• Comment out codes: select code in visual mode, then M-; (Alt + semicolon); this is universal for multiple languages supported by Emacs. C, Python, Clojure are verified.

• Use C-j instead of Enter to put cursor at the proper position (indention) of the next line;

• Modify C indent size to 4 space: add following code into ~/.emacs:

  (defun my-c-mode-common-hook () 
    (setq c-basic-offset 4) 
    (setq c-indent-level 4) 
    (setq tab-width 4)) 
  (add-hook 'c-mode-common-hook 'my-c-mode-common-hook)
  

• Format codes with right indents on region: C-M-\;

C Support

• List all key-bindings: F1 b;

• Open buffer in another window: C-x 4 b;

• Write a makefile, compile: M-x compile; run: M-! make run; After modification of source code, you just need [M-xM-! M-p] to do compile-run procedure, because M-p is the last command in shell mode.

Here is the demo C source file:

#include <stdio.h> 
int main () { 
  printf("hello world\n"); 
  return 0; 
}

"return 0:" is necessary, or the return value will be 12, which will be seen as a exception by the shell.