The difference between TCP and UDP in socket communication

1.TCP Server side:

#include <Winsock2.h>
#include <stdio.h>

void Main ()
{
WORD wversionrequested;
Wsadata Wsadata;
int err;

wversionrequested = Makeword (1, 1);

Err = WSAStartup (wversionrequested, &wsadata);
if (Err!= 0) {
Return
}

if (Lobyte (wsadata.wversion)!= 1 | |
Hibyte (wsadata.wversion)!= 1) {
WSACleanup ();
Return
}
SOCKET Socksrv=socket (af_inet,sock_stream,0);

Sockaddr_in addrsrv;
Addrsrv.sin_addr. S_un. S_addr=htonl (Inaddr_any);
Addrsrv.sin_family=af_inet;
Addrsrv.sin_port=htons (6000);

Bind (Socksrv, (sockaddr*) &addrsrv,sizeof (sockaddr));

Listen (socksrv,5);

Sockaddr_in addrclient;
int len=sizeof (SOCKADDR);

while (1)
{
SOCKET sockconn=accept (Socksrv, (sockaddr*) &addrclient,&len);
Char sendbuf[100];
sprintf (SendBuf, "Welcome%s to http://www.sunxin.org",
Inet_ntoa (ADDRCLIENT.SIN_ADDR));
Send (Sockconn,sendbuf,strlen (SENDBUF) +1,0);
Char recvbuf[100];
Recv (sockconn,recvbuf,100,0);
printf ("%s/n", recvbuf);
Closesocket (Sockconn);
}
}

2.TCP Client:

#include <Winsock2.h>
#include <stdio.h>

void Main ()
{
WORD wversionrequested;
Wsadata Wsadata;
int err;

wversionrequested = Makeword (1, 1);

Err = WSAStartup (wversionrequested, &wsadata);
if (Err!= 0) {
Return
}

if (Lobyte (wsadata.wversion)!= 1 | |
Hibyte (wsadata.wversion)!= 1) {
WSACleanup ();
Return
}
SOCKET Sockclient=socket (af_inet,sock_stream,0);

Sockaddr_in addrsrv;
Addrsrv.sin_addr. S_un. S_ADDR=INET_ADDR ("127.0.0.1");
Addrsrv.sin_family=af_inet;
Addrsrv.sin_port=htons (6000);
Connect (sockclient, (sockaddr*) &addrsrv,sizeof (sockaddr));

Char recvbuf[100];
Recv (sockclient,recvbuf,100,0);
printf ("%s/n", recvbuf);
Send (Sockclient, "This are Lisi", strlen ("This is Lisi") +1,0);

Closesocket (sockclient);
WSACleanup ();
}

3.UDP Server Side

#include <Winsock2.h>
#include <stdio.h>

void Main ()
{
WORD wversionrequested;
Wsadata Wsadata;
int err;

wversionrequested = Makeword (1, 1);

Err = WSAStartup (wversionrequested, &wsadata);
if (Err!= 0) {
Return
}

if (Lobyte (wsadata.wversion)!= 1 | |
Hibyte (wsadata.wversion)!= 1) {
WSACleanup ();
Return
}

SOCKET Socksrv=socket (af_inet,sock_dgram,0);
Sockaddr_in addrsrv;
Addrsrv.sin_addr. S_un. S_addr=htonl (Inaddr_any);
Addrsrv.sin_family=af_inet;
Addrsrv.sin_port=htons (6000);

Bind (Socksrv, (sockaddr*) &addrsrv,sizeof (sockaddr));

Sockaddr_in addrclient;
int len=sizeof (SOCKADDR);
Char recvbuf[100];

Recvfrom (socksrv,recvbuf,100,0, (sockaddr*) &addrclient,&len);
printf ("%s/n", recvbuf);
Closesocket (SOCKSRV);
WSACleanup ();
}

4.UDP Client

#include <Winsock2.h>
#include <stdio.h>

void Main ()
{
WORD wversionrequested;
Wsadata Wsadata;
int err;

wversionrequested = Makeword (1, 1);

Err = WSAStartup (wversionrequested, &wsadata);
if (Err!= 0) {
Return
}

if (Lobyte (wsadata.wversion)!= 1 | |
Hibyte (wsadata.wversion)!= 1) {
WSACleanup ();
Return
}

SOCKET Sockclient=socket (af_inet,sock_dgram,0);
Sockaddr_in addrsrv;
Addrsrv.sin_addr. S_un. S_ADDR=INET_ADDR ("127.0.0.1");
Addrsrv.sin_family=af_inet;
Addrsrv.sin_port=htons (6000);

SendTo (sockclient, "Hello", strlen ("Hello") +1,0,
(sockaddr*) &addrsrv,sizeof (sockaddr));
Closesocket (sockclient);
WSACleanup ();
}

The difference between TCP and UDP based on connection and connectionless requirements for system resources (TCP more, UDP less) UDP program structure simpler flow mode and datagram mode
TCP guarantees data correctness, UDP may lose packets
TCP guarantees data order, UDP does not guarantee

Specific programming when the difference between the parameters of the socket () different UDP server does not need to invoke listen and accept UDP transceiver data with the Sendto/recvfrom function TCP: Address information is determined when connect/accept
UDP: Address information must be specified each time in the Sendto/recvfrom function Udp:shutdown function is invalid

Some of the following requirements, should be adopted UDP-oriented datagram network data mostly for short messages have a large number of client for data security and no special requirements network burden is very heavy, but the response speed requires high

Example: ICQ, Ping