open 함수질문

#include <stdio.h>
#include <fcntl.h>
 
int main( )
{
        printf("O_RDONLY\t %8d\n", O_RDONLY);
        printf("O_WRONLY\t %8d\n", O_WRONLY);
        printf("O_RDWR\t %8d\n", O_RDWR);
        printf("O_APPEND\t %8d\n", O_APPEND);
        printf("O_TRUNC\t %8d\n", O_TRUNC);
        printf("O_EXCL\t %8d\n", O_EXCL);
        printf("O_CREAT\t %8d\n", O_CREAT);
        printf("\n");
        printf("S_IRUSR\t %8d\n", S_IRUSR);
        printf("S_IWUSR\t %8d\n", S_IWUSR);
        printf("S_IXUSR\t %8d\n", S_IXUSR);
        printf("S_IRGRP\t %8d\n", S_IRGRP);
        printf("S_IWGRP\t %8d\n", S_IWGRP);
        printf("S_IXGRP\t %8d\n", S_IXGRP);
        printf("S_IROTH\t %8d\n", S_IROTH);
        printf("S_IWOTH\t %8d\n", S_IWOTH);
        printf("S_IXOTH\t %8d\n", S_IXOTH);
        return 0;
}

O_RDONLY	        0
O_WRONLY	        1
O_RDWR	        2
O_APPEND	     1024
O_TRUNC	      512
O_EXCL	      128
O_CREAT	       64
 
S_IRUSR	      256
S_IWUSR	      128
S_IXUSR	       64
S_IRGRP	       32
S_IWGRP	       16
S_IXGRP	        8
S_IROTH	        4
S_IWOTH	        2
S_IXOTH	        1