Hello, given the following code (it's supposed to write "hellowolrd" in a "helloworld" file, and then read the text):

#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#define FNAME "helloworld"

int main(){ 
    int filedes, nbytes;
    char buf[128];

    /* Creates a file */
    if((filedes=open(FNAME, O_CREAT | O_EXCL | O_WRONLY | O_APPEND, 
        S_IRUSR | S_IWUSR)) == -1){
            write(2, "Error1\n", 7);
    }

    /* Writes hellow world to file */
    if(write(filedes, FNAME, 10) != 10)
        write(2, "Error2\n", 7);

    /* Close file */
    close(filedes);

    if((filedes = open(FNAME, O_RDONLY))==-1)
        write(2, "Error3\n", 7);

    /* Prints file contents on screen */    
    if((nbytes=read(filedes, buf, 128)) == -1)
        write(2, "Error4\n", 7);

    if(write(1, buf, nbytes) != nbytes)
        write(2, "Error5\n", 7);

    /* Close rile afte read */
    close(filedes); 

    return (0);
}

The first time i run the program, the output is:

helloworld

After that every time I to run the program, the output is:

Error1
Error2
helloworld

I don't understand why the text isn't appended, as I've specified the O_APPEND file. Is it because I've included O_CREAT ? It the file is already created, shouldn't O_CREAT be ignored ?