服务端代码：

#include

#include//套接字相关函数的头文件

#pragma comment(lib,"ws2_32.lib")//链接库文件

void main()

{

char SendBuf[100],ReceiveBuf[100];

int Length;

SOCKET socket_server,socket_receive;

SOCKADDR_IN Server_add,Client_add;

WSADATA wsaData;

WSAStartup(MAKEWORD(2,2),&wsaData);

Server_add.sin_family=AF_INET;//地址家族，必须为AF_INET

Server_add.sin_addr.S_un.S_addr=inet_addr("119.39.0.67");//IP地址，具体取决于你自己电脑上的地址

Server_add.sin_port=htons(5000);

socket_server=socket(AF_INET,SOCK_STREAM,0);

bind(socket_server,(SOCKADDR *)&Server_add,sizeof(SOCKADDR));

listen(socket_server,2);

Length=sizeof(SOCKADDR);

//下面这个语句，会一直等待，直到有客户端发送连接请求connect，这是阻塞模式

socket_receive=accept(socket_server,(SOCKADDR *)&Client_add,&Length);

printf("已有客户连接...\n");

while(1)

{

recv(socket_receive,ReceiveBuf,100,0);//阻塞模式，直有到数据发过来，才执行后面的语句

printf("%s\n",ReceiveBuf);

printf("Please enter message:");

scanf("%s",SendBuf);

send(socket_receive,SendBuf,100,0);//发送数据

}

}

客户端代码：

#include

#include

#pragma comment(lib,"ws2_32.lib")

void main()

{

char SendBuf[100],ReceiveBuf[100];

SOCKET sock_receive;

WSADATA wsaData;

WSAStartup(MAKEWORD(2,2),&wsaData);

SOCKADDR_IN Server_add;

Server_add.sin_family=AF_INET;//地址家族，必须为AF_INET

Server_add.sin_addr.S_un.S_addr=inet_addr("119.39.0.67");//IP地址，具体取决于你自己电脑上的地址

Server_add.sin_port=htons(5000);

sock_receive=socket(AF_INET,SOCK_STREAM,0);

connect(sock_receive,(SOCKADDR *)&Server_add,sizeof(SOCKADDR));

while(1)

{

printf("Please enter message:");

scanf("%s",SendBuf);

send(sock_receive,SendBuf,100,0);

recv(sock_receive,ReceiveBuf,100,0);

printf("%s\n",ReceiveBuf);

}

}

上面这个简易的聊天程序，只能按顺序聊天，也就是客户端先发送数据，发送过去之后，要想再发送数据，就必须等服务端发送数据过来。有点像呼叫机。

(转)UDP协议下的例子，客户端发送字符串给服务端，服务端将其转化成大写，再发回去。客户端接收并输出

服务端代码：

#include

#include

#include

#include

#pragma comment(lib,"ws2_32.lib")#define BUFSIZE 256

void main(void)

{struct sockaddr_in client,server;

SOCKET s;

in tlen,i,n;

char buf[BUFSIZE];

//初始化winsock

WSADATA wsaData;

WSAStartup(0x0202,&wsaData);

//建立套接字

s=socket(AF_INET,SOCK_DGRAM,0);

//初始化服务器地址结构

memset((char*)&server,0,sizeof(server));

server.sin_family =AF_INET;

server.sin_addr.S_un.S_addr=htonl(INADDR_ANY);

server.sin_port =htons(5320);

//绑定socket对象到服务器地址

bind(s,(struct sockaddr*)&server,sizeof(server));

//不需要初始化客户端地址结构

//接收客户端发送来的字符串，回送客户端

len=sizeof(client);

while((n=recvfrom(s,buf,BUFSIZE,0,(struct sockaddr*)&client,&len))>0)

{

for(i=0;i

buf[i]=toupper(buf[i]);

sendto(s,buf,n,0,(struct sockaddr*)&client,len);

}

//关闭socket

closesocket(s);

WSACleanup();

exit(0);

}

客户端代码：

#include

#include

#include

#include

#pragma comment(lib,"ws2_32.lib")

#define   BUFSIZE 256

void main(void)

{

struct  sockaddr_in client,server;

SOCKET s;

int len,zero,n;

char buf[BUFSIZE];

//初始化winsock

WSADATA wsaData;

WSAStartup(0x0202,&wsaData);

//建立套接字

s=socket(AF_INET,SOCK_DGRAM,0);

//初始化客户端地址结构

memset((char*)&client,0,sizeof(client));

client.sin_family =AF_INET;

client.sin_addr.S_un.S_addr=htonl(INADDR_ANY);

client.sin_port =htons(0);

//绑定socket对象到客户地址

bind(s,(struct sockaddr*)&client,sizeof(client));

//初始化服务器地址结构，确定要连接的服务器

memset((char*)&server,0,sizeof(server));

server.sin_family =AF_INET;

server.sin_addr.S_un.S_addr=inet_addr("202.202.42.88");//服务端IP地址

server.sin_port =htons(5320);

//客户端从键盘接受字符串，发送到服务器端，在从服务器端接收回送的字符串回显

len=sizeof(server);

while(1)

{

fgets(buf,BUFSIZE,stdin);

if(strncmp(buf,"exit",4)==0)break;

sendto(s,buf,strlen(buf),0,(struct sockaddr*)&server,len);

n=recvfrom(s,buf,BUFSIZE-1,0,(struct sockaddr*)&server,&len);

buf[n]='\0';//注意要添加字符串结束标志

fputs(buf,stdout);

}

fputs("bye bye!",stdout);

//关闭socket

closesocket(s);

WSACleanup();

exit(0);

}