C语言网络编程代码

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首先
project->settings->link 在object/library modules 中加入ws2_32.lib文件
在项目上点右键->属性->配置属性->链接器->输入->附加依赖项加入ws2_32.lib
winSock2.h文件里的变量和函数的符号链接放在ws2_32.lib里
该库对应ws2_32.dll，提供了对网络相关API的支持，若使用其中的API，则应该将ws2_32.lib加入工程（否则需要动态载入ws2_32.dll）。

一收一发版:

client _easy.c

#include <winsock2.h>
#include <stdio.h>
#include <windows.h>

int start_winsock()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    int err;

    wVersionRequested = MAKEWORD( 1, 1 );
    err = WSAStartup(wVersionRequested, &wsaData );
    if ( err != 0 ) {
        return -1;
    }
    if (LOBYTE( wsaData.wVersion ) != 1
               || HIBYTE(wsaData.wVersion) != 1 ) {
        WSACleanup( );
        return -1;
    }
}

int set_conn_socket(SOCKET *sock)
{
    int err;
    char  addr[100];
    *sock = socket(AF_INET, SOCK_STREAM, 0);
    //设置通信地址
    SOCKADDR_IN addrSrv;
    printf("请输入服务器的IP地址\n");
    gets(addr);
    addrSrv.sin_addr.S_un.S_addr = inet_addr(addr);      // 本地回路地址是127.0.0.1;
    addrSrv.sin_family = AF_INET;
    addrSrv.sin_port = htons(6000);
      //把socket与地址绑定在一起
    err = connect(*sock, (SOCKADDR*)&addrSrv, sizeof(SOCKADDR));
    if (err != 0){
        return -1;
    }
}
int main()
{
    int err;
    char sendBuf[100], recvBuf[100];
    SOCKET sockClient;
    int ret;
    if(start_winsock() == -1)
        return 0;
    err = set_conn_socket(&sockClient);
    if(err == -1){
        printf("连接失败，退出!");
    } else
        printf("连接成功，开始通信：\n");

    while(1){
        recv(sockClient, recvBuf, 100, 0);
        printf("Says: %s\n", recvBuf);     // 接收信息
        gets(sendBuf);
        //char sendBuf[100] = {"hello, I am here"};
        send(sockClient, sendBuf, strlen(sendBuf)+1, 0);
    }

}

server _easy.c

#include <winsock2.h>
#include <stdio.h>
#include <windows.h>

int start_winsock()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    int err;

    wVersionRequested = MAKEWORD( 1, 1 );
    err = WSAStartup(wVersionRequested, &wsaData );
    if ( err != 0 )
    {
        return -1;
    }
    if (LOBYTE( wsaData.wVersion ) != 1
            || HIBYTE(wsaData.wVersion) != 1 )
    {
        WSACleanup( );
        return -1;
    }
}

void set_socket(SOCKET *sock)
{
    *sock = socket(AF_INET, SOCK_STREAM, 0);
    //设置通信地址
    SOCKADDR_IN addrSrv;
    addrSrv.sin_addr.S_un.S_addr = htonl(INADDR_ANY); // 将INADDR_ANY转换为网络字节序，调用 htonl(long型)或htons(整型)
    addrSrv.sin_family = AF_INET;
    addrSrv.sin_port = htons(6000);
    //把socket与地址绑定在一起
    bind(*sock, (SOCKADDR*)&addrSrv, sizeof(SOCKADDR));

    listen(*sock, 10);
}
void wait_conn(SOCKET *sockser, SOCKET *sockcli)
{
    SOCKADDR_IN  addrClient;
    int len = sizeof(SOCKADDR);

    printf("正在等待客户连接！！\n");
    *sockcli = accept(*sockser, (SOCKADDR*)&addrClient, &len);
    printf("连接成功，开始通信：\n");
}
int main()
{
    SOCKET sockSrv, sockConn;
    char sendBuf[100], recvBuf[100];

    int ret;

    if(start_winsock() == -1)
        return 0;
    set_socket(&sockSrv);

    wait_conn(&sockSrv,&sockConn);

    while(1)
    {
        gets(sendBuf);
             //char sendBuf[100] = {"hello, I am here"};
        send(sockConn, sendBuf, strlen(sendBuf)+1, 0);  // 发送显示欢迎信息
        recv(sockConn, recvBuf, 100, 0);
        printf("Says: %s\n", recvBuf);     // 接收信息
    }
}

多收多发版:
client.c

#include <winsock2.h>
#include <stdio.h>
#include <windows.h>

int start_winsock()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    int err;

    wVersionRequested = MAKEWORD( 1, 1 );
    err = WSAStartup(wVersionRequested, &wsaData );
    if ( err != 0 ) {
        return -1;
    }
    if (LOBYTE( wsaData.wVersion ) != 1
               || HIBYTE(wsaData.wVersion) != 1 ) {
        WSACleanup( );
        return -1;
    }
}

int set_conn_socket(SOCKET *sock)
{
    int err;
    char  addr[100];
    *sock = socket(AF_INET, SOCK_STREAM, 0);
    //设置通信地址
    SOCKADDR_IN addrSrv;
    printf("请输入服务器的IP地址\n");
    gets(addr);
    addrSrv.sin_addr.S_un.S_addr = inet_addr(addr);      // 本地回路地址是127.0.0.1;
    addrSrv.sin_family = AF_INET;
    addrSrv.sin_port = htons(6000);
      //把socket与地址绑定在一起
    err = connect(*sock, (SOCKADDR*)&addrSrv, sizeof(SOCKADDR));

    if (err != 0){
        return -1;
    }
}
int main()
{
    int err;
    char sendBuf[100], recvBuf[100];
    SOCKET sockClient;
    struct timeval timeout = {1,0};
    struct fd_set rfds;
    int ret;
    
    if(start_winsock() == -1)
        return 0;
    err = set_conn_socket(&sockClient);
    if(err == -1){
        printf("连接失败，退出!");
    } else
        printf("连接成功，开始通信：\n");

    while(1){
        FD_ZERO(&rfds);  /* 清空集合 */
        FD_SET(sockClient, &rfds);  /* 这里是添加检测 */

        ret=select(0, &rfds, NULL, NULL, &timeout);
        if(ret > 0)
        {
            if(FD_ISSET(sockClient,&rfds))  /* 这里检测的是fp在集合中是否状态变化，即可以操作。 */
            {
                recv(sockClient, recvBuf, 100, 0);
                printf("Says: %s\n", recvBuf);     // 接收信息
            }
        }

        if(kbhit()) {
            gets(sendBuf);
        //char sendBuf[100] = {"hello, I am here"};
            send(sockClient, sendBuf, strlen(sendBuf)+1, 0);
        }
    }
}

server.c

#include <winsock2.h>
#include <stdio.h>
#include <windows.h>

int start_winsock()
{
    WORD wVersionRequested;
    WSADATA wsaData;
    int err;

    wVersionRequested = MAKEWORD( 1, 1 );
    err = WSAStartup(wVersionRequested, &wsaData );
    if ( err != 0 )
    {
        return -1;
    }
    if (LOBYTE( wsaData.wVersion ) != 1
            || HIBYTE(wsaData.wVersion) != 1 )
    {
        WSACleanup( );
        return -1;
    }
}

void set_socket(SOCKET *sock)
{
    *sock = socket(AF_INET, SOCK_STREAM, 0);
    //设置通信地址
    SOCKADDR_IN addrSrv;
    addrSrv.sin_addr.S_un.S_addr = htonl(INADDR_ANY); // 将INADDR_ANY转换为网络字节序，调用 htonl(long型)或htons(整型)
    addrSrv.sin_family = AF_INET;
    addrSrv.sin_port = htons(6000);
    //把socket与地址绑定在一起
    bind(*sock, (SOCKADDR*)&addrSrv, sizeof(SOCKADDR));
    listen(*sock, 10);
}
void wait_conn(SOCKET *sockser, SOCKET *sockcli)
{
    SOCKADDR_IN  addrClient;
    int len = sizeof(SOCKADDR);

    printf("正在等待客户连接！！\n");
    *sockcli = accept(*sockser, (SOCKADDR*)&addrClient, &len);
    printf("连接成功，开始通信：\n");
}
int main()
{
    SOCKET sockSrv, sockConn;
    char sendBuf[100], recvBuf[100];
    struct timeval timeout = {1,0};
    struct fd_set rfds;
    int ret;

    if(start_winsock() == -1)
        return 0;
    set_socket(&sockSrv);
    wait_conn(&sockSrv,&sockConn);

    while(1)
    {
        if(kbhit()) {
            gets(sendBuf);
            send(sockConn, sendBuf, strlen(sendBuf)+1, 0);  // 发送显示欢迎信息
        }
        FD_ZERO(&rfds);  /* 清空集合 */
        FD_SET(sockConn, &rfds);  /* 这里是添加检测 */

        ret=select(0, &rfds, NULL, NULL, &timeout);
        if(ret > 0)
        {
            if(FD_ISSET(sockConn,&rfds))  /* 这里检测的是fp在集合中是否状态变化，即可以操作。 */
            {
                ret = recv(sockConn, recvBuf, 100, 0);
                if (ret > 0) //大于0才是有意义的数据，防止对方掉线打印无用信息
                printf("Says: %s\n", recvBuf);     // 接收信息
            }
        }
    }
}