vim keyword completion

How do i tell vim editor about my include files path, so that it can auto complete the function names when i press control+N.

For example, I have c program like below

#include<stdio.h>
int main()
{
    sca //here i press control+N, it doesnot complete to scanf
}

From stackoverflow

• In your .vimrc add the paths to your .vimrc

  set path+=/usr/include/**
  set path+=/my_include_dir/include
  set path+=/my_include_dir/srclib/apr/**
  set path+=/my_other_include_dir/srclib/apr-util/**
  
  ** means all sub-directories.
  *  means all contained directories
  .  means all files in the directory of the found file
  += means prepend to existing path (iirc)
  

  You can check the paths as well by opening your file and then entering

  :checkpath
  

  This will give you a list of all included files that are missing. N.B. It doesn't seem to handle preprocessor directives, so you will get some false positives. Entering

  :checkpath!
  

  Will give a complete list of found and missing include files.

  HTH

  cheers,

  Rob

• Also, Important to note there are many completion functions.

  ^x ^o  = "omnicomplete" 
  ^x ^i  = "included-files completion" 
  ^x ^f  = "path completion" 
  ^x ^l  = "Complete this line using one that looks the same"
  

  see

  :help ins-completion
  

  for more.

• Vim might also know the path already, if the files are in a standard location. <C-n> uses the 'complete' option and the flag i scans included files. To add i to 'complete':

  set complete+=i

  you can also get a tags file from the symbols you want completed, which you can use with:

  set complete+=t