编译时注意添加 -lwsock32

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

void error_handling(char *message) ;

int main(int argc, char* argv[]) {
    WSADATA wsaData;
    SOCKET hSocket;
    SOCKADDR_IN servAddr;

    char message[] = "Hello world";
    int strLen;
    if (argc != 3) {
        printf("Usage: %s <IP><post>\n", argv[0]);
        exit(1);
    }


    if (WSAStartup(MAKEWORD(2,2), &wsaData) !=0)
        error_handling("WSAStartup() error");

    hSocket = socket(PF_INET, SOCK_STREAM, 0);
    if(hSocket == INVALID_SOCKET) {
        error_handling("socket() error");
    }

    memset(&servAddr, 0, sizeof(servAddr));
    servAddr.sin_family = AF_INET;
    servAddr.sin_addr.s_addr = inet_addr(argv[1]);
    servAddr.sin_port = htons(atoi(argv[2]));

    if (connect(hSocket, (SOCKADDR*)&servAddr, sizeof(servAddr)) == SOCKET_ERROR)
        error_handling("connect error");
    strLen = recv(hSocket, message, sizeof(message)-1,0);
    if (strLen == -1) {
        error_handling("read error");
    }
    printf("Message from Server: %s \n", message);
    closesocket(hSocket);
    printf("over");
    WSACleanup();
    return 0;
}

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