回声服务器端/客户端（不使用线程）

服务器：

#include<stdio.h>
#include<stdlib.h>
#include<winsock.h>
void error_handling(char* message);
#define BUF_SIZE 1024
int main()
{
    WSADATA wsaData;
    SOCKET hServSock, hClntSock;
    SOCKADDR_IN servAddr, clntAddr;
    char message[BUF_SIZE];
    int strLen,i;
    int clntAdrSize;
    if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0)
    {
        error_handling("WSAStartup() error");
    }
    hServSock = socket(PF_INET, SOCK_STREAM, 0);
    if (hServSock == INVALID_SOCKET)
    {
        error_handling("socket() error");
    }

    memset(&servAddr, 0, sizeof(servAddr));
    servAddr.sin_family = AF_INET;
    servAddr.sin_addr.s_addr =  inet_addr("127.0.0.1");
    servAddr.sin_port = htons(9190);
    if (bind(hServSock, (SOCKADDR*)& servAddr, sizeof(servAddr)) == SOCKET_ERROR)
    {
        error_handling("bind() error");
    }
    if (listen(hServSock, 5) == SOCKET_ERROR)
    {
        error_handling("listen() error");
    }
    clntAdrSize = sizeof(clntAddr);

    for(i = 0;i < 5;i++)
    {
        hClntSock = accept(hServSock,(SOCKADDR*)&clntAddr,&clntAdrSize);
        if(hClntSock == -1)
        {
            error_handling("accept() error");
        }
        else
        {
            printf("Connected client %d 
",i+1);
        }
        while((strLen = recv(hClntSock,message,BUF_SIZE,0))!=0)
        {
            send(hClntSock,message,strLen,0);
        }
        closesocket(hClntSock);
    }
    closesocket(hServSock);
    WSACleanup();
    return 0;
}

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

客户端：

#include<stdio.h>
#include<stdlib.h>
#include<winsock.h>
void error_handling(char* message);
#define Buf_Size 1024
int main()
{
    WSADATA wsaData;
    SOCKET hSocket;
    SOCKADDR_IN servAdr;
    char message[1024];
    int strLen;

    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(&servAdr, 0, sizeof(servAdr));
    servAdr.sin_family = AF_INET;
    servAdr.sin_addr.s_addr = inet_addr("127.0.0.1");
    servAdr.sin_port = htons(9190);
    
    if(connect(hSocket,(SOCKADDR*)&servAdr,sizeof(servAdr)) == SOCKET_ERROR)
        error_handling("connect() error");
    else
        puts("Connected............");
    while(1)
    {
        fputs("Input message(Q to quit): ",stdout);
        fgets(message,Buf_Size,stdin);
        if(!strcmp(message,"q
") || !strcmp(message,"Q
"))
        {
            break;
        }
        send(hSocket,message,strlen(message),0);
        strLen = recv(hSocket,message,Buf_Size-1,0);
        message[strLen] = 0;
        printf("Message from sever: %s",message);
    }
    closesocket(hSocket);
    WSACleanup();
    return 0;
}

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