what is the error code of stat for non existent file ?

Hello ,...
how to know if file exists or not.

i use to use stat() but i can't find out what exit code or how to know if file dosnot exists.
i thout that stat() will return some error but i can't find any :
i use to use this :

Code:

int exit_code_of_state = -9999; 
exit_code_of_state  ==  stat (filename, &stat_p);

but it won't give me any error if a directory dosen't exists

and i know that if stat had error code of -1 he can't state it but if the file dosent exists i don't know how to know that
also how do i use the '~' sign (the user home dir) since i dosent work with (~/.myprogram) directly from c (like i did here)

Code:

#include <sys/stat.h>			/* declare the 'stat' structure	*/
#include <sys/types.h>			
#include <unistd.h>		
#include <stdio.h>			/* printf			*/
#include <time.h>

#define  FILENAME "~/.myprog/"		/* PUT YOUR FILE NAME HERE	*/

/************************************************************************/

char * format_time(time_t cal_time);


/************************************************************************/

int main()
{
  file_stat(FILENAME);
	return 0;
}

/************************************************************************/

void file_stat(char * filename)
{
  struct stat stat_p;		/* 'stat_p' is a pointer to a structure
				 * of type 'stat'.  			*/

				/* Get stats for file and place them in
				 * the structure.			*/
  int exit_code_of_state = -9999;//to see that the exit code can be changed
  exit_code_of_state ==(int)  stat (filename, &stat_p);
  
  if ( exit_code_of_state == -1)
  {
    printf(" Error occoured attempting to stat %s\n", filename);
    exit(0);
  }
				/* Print a few structure members.	*/
  
  
  if (stat_p.st_size == 0 )
  {
	  //the dir dosen't exists
	  printf("The dir dosn't exists\n creating new one ");
	  mkdir(FILENAME , S_IRWXU);
  }
  else
  {
	return;
  }
  
}

~ is expanded by the shell, not by low level API calls.

Read the manual page for stat().

Originally Posted by a man page

RETURN VALUE
On success, zero is returned. On error, -1 is returned,
and errno is set appropriately.

ERRORS
EBADF filedes is bad.

ENOENT A component of the path file_name does not exist,
or the path is an empty string.