socket学习笔记——select函数的使用（windows)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <winsock2.h>

#define BUF_SIZE 1024
void error_handling(char* message);

int main(int argc, char* argv[])
{
    WSADATA wsadata;
    SOCKET hServSock, hClntSock;
    SOCKADDR_IN servAddr, clntAddr;
    TIMEVAL timeout;
    fd_set reads, cp_reads;

    int adr_sz;
    int str_len, i,fd_num;
    char buf[BUF_SIZE];

    if (argc != 2)
    {
        printf("usage:%s <port>
",argv[0]);
        exit(1);
    }
    if (WSAStartup(MAKEWORD(2, 2), &wsadata) != 0)
        error_handling("WSAStartup error");

    hServSock = socket(PF_INET, SOCK_STREAM, 0);
    memset(&servAddr, 0, sizeof(servAddr));
    servAddr.sin_family = AF_INET;
    servAddr.sin_addr.S_un.S_addr = htonl(INADDR_ANY);
    servAddr.sin_port = htons(atoi(argv[1]));

    if (bind(hServSock, (SOCKADDR*)&servAddr, sizeof(servAddr)) == SOCKET_ERROR)
        error_handling("bind error");
    if (listen(hServSock, 5) == SOCKET_ERROR)
        error_handling("listen error");

    FD_ZERO(&reads);
    FD_SET(hServSock, &reads);

    while (1)
    {
        cp_reads = reads;
        timeout.tv_sec = 5;

        if ((fd_num = select(0, &cp_reads, 0, 0, &timeout)) == SOCKET_ERROR)
            break;
        if (fd_num == 0)
            continue;

        for (i = 0;i < reads.fd_count;i++)
        {
            if (FD_ISSET(reads.fd_array[i], &cp_reads))
            {
                if (reads.fd_array[i] == hServSock)
                {
                    adr_sz = sizeof(clntAddr);
                    hClntSock = accept(hServSock, (SOCKADDR*)&servAddr, &adr_sz);
                    FD_SET(hClntSock, &reads);
                    printf("connected client:%d
", hClntSock);
                }
                else
                {
                    str_len = recv(reads.fd_array[i], buf, BUF_SIZE - 1, 0);
                    if (str_len == 0)
                    {
                        FD_CLR(reads.fd_array[i], &reads);
                        closesocket(cp_reads.fd_array[i]);
                        printf("closed client:%d
", cp_reads.fd_array[i]);
                    }
                    else
                        send(reads.fd_array[i], buf, str_len, 0);
                }
            }
        }
    }
    closesocket(hServSock);
    WSACleanup();
    return 0;
}

void error_handling(char* message)
{
    fputs(message, stderr);
    fputc('
', stderr);
    exit(1);
}