C++实现UDP通信。。

void main()
{
WORD wVersionRequested;//定义一个word类型的变量
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;
}

//第一步同样的创建套接字
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);

//绑定套接字
bind(socksrv,(SOCKADDR*)&addrsrv,sizeof(SOCKADDR));
/*接收数据 此处与TCP不同
int recvfrom(
SOCKET s,
char FAR* buf,  接收数据的buf
int len,                     长度
int flags,                  0
struct sockaddr FAR *from,   地址结构体指针，表明是一个返回izhi
int FAR *fromlen      设置初始值，并且有返回值      );

首先定义地址结构的变量
*/
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();

}

#include<iostream>
#include<Winsock2.h>
#pragma comment(lib,"WS2_32")
using namespace std;
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);
cout<<recvBuf<<endl;
closesocket(sockSrv);
WSACleanup();
}

void main()
{
WORD wVersionRequested;//定义一个word类型的变量
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;
}

//第一步同样是新建套接字
SOCKET sockClient=socket(AF_INET,SOCK_DGRAM,0);
//第二步直接发送数据 用sendto函数
/*
int sendto(
SOCKET s,
const char FAR *buf,
int len,
int flags,
const struct sockaddr FAR *to,  设定目的套接字的地址结构体信息
int tolen        地址结构体长度                );

*/
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();

}

#include<iostream>
#include<Winsock2.h>
#pragma comment(lib,"WS2_32")
using namespace std;
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();
}