C's printf and fprintf(stdout,) are not printing - c

Question

This is a bit of an odd one. My code wasn't outputting what I thought it should. I added some print statements at various stages to see where it was going wrong. Still nothing.
So I added a printf statement at the start of main. That's where I got really confused.
So I presumed something funny was happening with the file descriptors. I changed the printf to a fprintf. Still nothing. Printing to stderr with fprintf does work! Why is this happening?
Removing all of the body from main except the initial print statement and the return does print.
Code
int main(void) {
fprintf(stdout, "STARTED!");
//Create an Internet domain socket
int sockfd = socket(AF_INET, SOCK_STREAM, 0);
//If this fails exit and print the error
if (sockfd == -1) {
printf("Error %d, cannot create socket", errno);
return 1;
}
printf("SOCKET CREATED!");
//Creates a socket address
struct sockaddr_in addr;
addr.sin_family = AF_INET;
addr.sin_port = htons(8080);
addr.sin_addr.s_addr = INADDR_ANY;
//Attempts to bind to the socket address, again prints to error if this fails.
if (bind(sockfd, (struct sockaddr *) &addr, sizeof(addr)) == -1)
{
printf("Error %d, cannot bind", errno);
return 1;
}
//Starts Listening for a client
if (listen(sockfd, 1) == -1)
{
printf("Error %d, cannot listen", errno);
return 1;
}
//If all is successful, server is operational
while(1)
{
//Creates a file descripter for the connection
int connfd;
//And a socket address for the client
struct sockaddr_in cliaddr;
socklen_t cliaddrlen = sizeof(cliaddr);
//If a connection attempt is made accepts it.
connfd = accept(sockfd, (struct sockaddr *) &cliaddr, &cliaddrlen);
if (connfd == -1) {
//If the connection fails print an error
printf("Error %d, cannot accept connection", errno);
continue;
}
//Otherwise process the request
else {
printf("CONNECTED!");
char end;
end = 1;
while (end)
{
process_request(connfd);
end = 0;
}
}
close(connfd);
}
close(sockfd);
return 0;
}

Answer 1

Output is often buffered by the system. You can call fflush, but sometimes, depending on how the caching works, simply ending the output with a newline is sufficient. So try changing
fprintf(stdout, "STARTED!");
to
fprintf(stdout, "STARTED!\n");
And, if that doesn't help, to
fprintf(stdout, "STARTED!\n");
fflush(stdout)
(And stderr often isn't cached, as you want to see errors immediately.)
Finally, you will see output when the program finishes (as things are flushed then), which probably explains the rest of the behaviour.