Thread: error in creat file by using 'open' function

hi I am just write a simple program(c.c) :

Code:

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
int main()
{
   int fp;
   char * pathname = "/dream/dream.txt";
   if((fp=open(pathname,O_WRONLY))==-1)
	printf("error in open file\n");
   write(fp,pathname,11);
   close(fp);
   return 0;
}

I can build it with gcc -o c c.c,it 's no error but when exec it ,it can't write the string in the file 'dream.txt' . when i rebuild it with 'gcc -Wall -o c c.c',It print that:

Code:

c.c: In function ‘main’:
c.c:14: warning: implicit declaration of function ‘write’
c.c:15: warning: implicit declaration of function ‘close’

can you tell me why?
Thanks !!