網絡編程：UDP編程

基於UDP編程（服務器端持續監聽客戶端的請求）

服務器端 server.cpp：

#include <stdio.h>
#include <winsock2.h>
#pragma comment (lib, "ws2_32.lib")  //加載 ws2_32.dll

#define BUF_SIZE 100

int main(){
    WSADATA wsaData;
    WSAStartup( MAKEWORD(2, 2), &wsaData);

    //創建套接字
    SOCKET sock = socket(AF_INET, SOCK_DGRAM, 0);

    //綁定套接字
    sockaddr_in servAddr;
    memset(&servAddr, 0, sizeof(servAddr));  //每個字節都用0填充
    servAddr.sin_family = PF_INET;  //使用IPv4地址
    servAddr.sin_addr.s_addr = htonl(INADDR_ANY); //自動獲取IP地址
    servAddr.sin_port = htons(1234);  //端口
    bind(sock, (SOCKADDR*)&servAddr, sizeof(SOCKADDR));

    //接收客戶端請求
    SOCKADDR clntAddr;  //客戶端地址信息
    int nSize = sizeof(SOCKADDR);
    char buffer[BUF_SIZE];  //緩衝區
    while(1){
        int strLen = recvfrom(sock, buffer, BUF_SIZE, 0, &clntAddr, &nSize);
        sendto(sock, buffer, strLen, 0, &clntAddr, nSize);
    }

    closesocket(sock);
    WSACleanup();
    return 0;
}

客戶端 client.cpp：

#include <stdio.h>
#include <WinSock2.h>
#pragma comment(lib, "ws2_32.lib")  //加載 ws2_32.dll

#define BUF_SIZE 100

int main(){
    //初始化DLL
    WSADATA wsaData;
    WSAStartup(MAKEWORD(2, 2), &wsaData);

    //創建套接字
    SOCKET sock = socket(PF_INET, SOCK_DGRAM, 0);

    //服務器地址信息
    sockaddr_in servAddr;
    memset(&servAddr, 0, sizeof(servAddr));  //每個字節都用0填充
    servAddr.sin_family = PF_INET;
    servAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
    servAddr.sin_port = htons(1234);

    //不斷獲取用戶輸入併發送給服務器，然後接受服務器數據
    sockaddr fromAddr;
    int addrLen = sizeof(fromAddr);
    while(1){
        char buffer[BUF_SIZE] = {0};
        printf("Input a string: ");
        gets(buffer);
        sendto(sock, buffer, strlen(buffer), 0, (struct sockaddr*)&servAddr, sizeof(servAddr));
        int strLen = recvfrom(sock, buffer, BUF_SIZE, 0, &fromAddr, &addrLen);
        buffer[strLen] = 0;
        printf("Message form server: %s\n", buffer);
    }

    closesocket(sock);
    WSACleanup();
    return 0;
}