To drive these points home, it will be useful to work through a full UDP client and UDP server program.
To keep things simple, we will create a UDP client program that simply sends the Hello World string to 127.0.0.1 on port 8080. Our UDP server listens on 8080. It prints any data it receives, along with the sender's address and port number.
We will begin by implementing the simple UDP server.
We will start with the server, since we already have a usable UDP client, that is, udp_client.c.
Like all of our networked programs, we will begin by including the necessary headers, starting with the main() function, and initializing Winsock as follows:
/*udp_recvfrom.c*/
#include "chap04.h"
int main() {
#if defined(_WIN32)
WSADATA d;
if (WSAStartup(MAKEWORD(2, 2), &d)) {
fprintf(stderr, "Failed to initialize.\n");
return 1;
}
#endifIf you've been working through this book in order, this code should be very routine for you...