#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <errno.h>

#define NUM_NAMES 5
#define BLOCK_SIZE 10

int main(int argc, char** argv) {

	int fd = open("test.txt", O_WRONLY|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR);
	if (fd < 0) {
		fprintf(stderr, "return from open %d\n", fd);
		return 1;
	}

	char names[NUM_NAMES][BLOCK_SIZE] = {"Adam", "Bob", "Cathy", "Daniel", "Edward"};

	int i;
	for (i = 0; i < NUM_NAMES; ++i) {

		/* move to the beginning of block
		   a name will start at the beginning of every 10 bytes */
		int r = lseek(fd, BLOCK_SIZE*i, SEEK_SET);
		if (r < 0) {
			fprintf(stderr, "return from lseek unexpected -- %d -- %s\n", 
				r, strerror(errno));
			return 1;
		}
		
		/* size of string plus a null char */
		int len = strlen(names[i]) + 1;
		r = write(fd, names[i], len);
		if (r != len) {
			fprintf(stderr, "return from write unexpected -- %d -- %s\n", 
				r, strerror(errno));
			return 1;
		}
	}

	close(fd);
	return 0;
}