#include <sys/select.h> #include <sys/socket.h> #include <arpa/inet.h> #define MAX_DATA_BUF_LEN 10240 int sd = INVALID_SOCKET; sockaddr_in addr_org;  // 发送端地址 sd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);  // 创建socket addr_org.sin_family = AF_INET; addr_org.sin_addr.s_addr = inet_addr("192.128.0.1");  // 发送端IP addr_org.sin_port = htons(8080);  // 发送端端口 bind(sd, (struct sockaddr *)&(addr_org), sizeof(struct sockaddr_in));  // 绑定IP和端口

sockaddr_in addr_dst;  // 接收端地址 addr_dst.sin_family = AF_INET; addr_dst.sin_addr.s_addr = inet_addr("192.128.0.2");  // 接收端IP addr_dst.sin_port = htons(8080);  // 接收端端口 ... // 生成要发送的数据到SendDataBuff, 长度为ulLen sendto(sd, SendDataBuff, ulLen, 0, (struct sockaddr *)&(addr_dst), sizeof(sockaddr_in));  // 发送SendDataBuff中的数据

void *SocketReceiveThread(void *pParam) {     fd_set fdset;     struct timeval delayval;     unsigned long lRetVal;     delayval.tv_sec  = 0;     delayval.tv_usec = 5000;    /*5ms延时*/     while (!end_flag)     {         FD_ZERO(&fdset);         FD_SET(sd, &fdset);         lRetVal = select(sd+1, &fdset, NULL, NULL, &delayval); // 尤其要注意第一个参数         if (0 == lRetVal)         {             continue;         }         else if (SOCKET_ERROR == lRetVal)         {             break;         }         else if (FD_ISSET(sd, &fdset) != 0)         {             char RecvDataBuff[MAX_DATA_BUF_LEN];  // 接收数据buffer             unsigned long ulLen = recvfrom(sd, RecvDataBuff, MAX_DATA_BUF_LEN, 0, NULL, NULL);             ... // 处理接收到的数据         }     } }