write to stdout after closing it?

gistfile1.txt

/* doesn't work */

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

int main() {
	close(STDOUT_FILENO);
	if (open("/dev/null", O_WRONLY) != STDOUT_FILENO) {
		fprintf(stderr, "Could not open /dev/null as fd %d", STDOUT_FILENO);
		return 1;
	}

	int out2 = open("/dev/stdout", O_WRONLY);
	if (out2 == -1) {
		perror("Could not open /dev/stdout:");
		return 1;
	}
	dprintf(out2, "Hello world.");
	return 0;
}