socket udp 與tcp 區別

1.TCP服務器端:

#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客戶端：

#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 is lisi",strlen("This is lisi")+1,0);

closesocket(sockClient);
WSACleanup();
}

3.UDP服務器端

#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客戶端

#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();
}

TCP與UDP的區別

基於連接與無連接
對系統資源的要求（TCP較 多，UDP少）
UDP程序結構較簡單
流模式與數據報模式
TCP保證數據正確性，UDP可能丟包
TCP 保證數據順序，UDP不保證
具體編程時的區別

socket() 的參數不同
UDP Server不需要調用listen和accept
UDP收發數據用 sendto/recvfrom函數
TCP：地址信息在connect/accept時確定
UDP：在 sendto/recvfrom函數中每次均 需指定地址信息
UDP：shutdown函數無效
部分滿足以下幾點要求時，應該采用UDP 面向數據報方式

網絡數據大多為短消息
擁 有大量Client
對數據安全性無特殊要求
網絡負擔非常重，但對響應速度要求高