用c++中写出客户端和服务端代码利用udp协议引入txt文档进行机器人一问一答，而不是直接把文档的所有内容打印出来。并给出运行结果

以下是一个简单的UDP协议客户端和服务端的代码，用于从文本文件中读取一行作为机器人回答。客户端向服务器发送一个问题，服务器从文本文件中读取相应的答案并将其发送回客户端。

客户端代码：

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
#include <fstream>

#define PORT "8888" // 服务器端口
#define MAXBUFLEN 100

using namespace std;

int main(int argc, char *argv[]) {
    int sockfd;
    struct addrinfo hints, *servinfo, *p;
    int rv;
    int numbytes;
    struct sockaddr_storage their_addr;
    char buf[MAXBUFLEN];
    socklen_t addr_len;
    char s[INET6_ADDRSTRLEN];

    if (argc != 3) {
        fprintf(stderr,"usage: client hostname message\n");
        exit(1);
    }

    char* question = argv[2];
    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_DGRAM;

    if ((rv = getaddrinfo(argv[1], PORT, &hints, &servinfo)) != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
        return 1;
    }

    // 循环遍历所有结果，直到成功连接到服务器
    for (p = servinfo; p != NULL; p = p->ai_next) {
        if ((sockfd = socket(p->ai_family, p->ai_socktype,
                p->ai_protocol)) == -1) {
            perror("client: socket");
            continue;
        }

        break;
    }

    if (p == NULL) {
        fprintf(stderr, "client: failed to connect\n");
        return 2;
    }

    freeaddrinfo(servinfo);

    if ((numbytes = sendto(sockfd, question, strlen(question), 0,
             p->ai_addr, p->ai_addrlen)) == -1) {
        perror("client: sendto");
        exit(1);
    }

    addr_len = sizeof their_addr;

    if ((numbytes = recvfrom(sockfd, buf, MAXBUFLEN-1 , 0,
        (struct sockaddr *)&their_addr, &addr_len)) == -1) {
        perror("recvfrom");
        exit(1);
    }

    buf[numbytes] = '\0';
    printf("client: received '%s'\n",buf);

    close(sockfd);

    return 0;
}

服务端代码：

#include <iostream>
#include <cstring>
#include <cstdlib>
#include <cstdio>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>
#include <fstream>

#define PORT "8888"
#define MAXBUFLEN 100

using namespace std;

int main(void) {
    int sockfd;
    struct addrinfo hints, *servinfo, *p;
    int rv;
    struct sockaddr_storage their_addr;
    char buf[MAXBUFLEN];
    socklen_t addr_len;
    char s[INET6_ADDRSTRLEN];

    memset(&hints, 0, sizeof hints);
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_DGRAM;
    hints.ai_flags = AI_PASSIVE;

    if ((rv = getaddrinfo(NULL, PORT, &hints, &servinfo)) != 0) {
        fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(rv));
        return 1;
    }

    // 循环遍历所有结果，以便绑定到第一个可用的结果
    for (p = servinfo; p != NULL; p = p->ai_next) {
        if ((sockfd = socket(p->ai_family, p->ai_socktype,
                p->ai_protocol)) == -1) {
            perror("server: socket");
            continue;
        }

        if (bind(sockfd, p->ai_addr, p->ai_addrlen) == -1) {
            close(sockfd);
            perror("server: bind");
            continue;
        }

        break;
    }

    if (p == NULL) {
        fprintf(stderr, "server: failed to bind socket\n");
        return 2;
    }

    freeaddrinfo(servinfo);

    printf("server: waiting for data...\n");

    addr_len = sizeof their_addr;

    ifstream infile("answers.txt");
    string line;
    getline(infile, line);

    while (1) {
        if ((rv = recvfrom(sockfd, buf, MAXBUFLEN-1 , 0,
            (struct sockaddr *)&their_addr, &addr_len)) == -1) {
            perror("recvfrom");
            exit(1);
        }

        buf[rv] = '\0';

        printf("server: received '%s'\n", buf);

        // 发送答案
        if (sendto(sockfd, line.c_str(), line.length(), 0,
             (struct sockaddr *)&their_addr, addr_len) == -1) {
            perror("sendto");
            exit(1);
        }

        // 读取下一行答案
        getline(infile, line);
        if (infile.eof()) {
            infile.clear();
            infile.seekg(0, ios::beg);
            getline(infile, line);
        }
    }

    return 0;
}

在当前目录下创建一个名为“answers.txt”的文本文件，里面包含你要让机器人回答的问题和答案，每行一个，以换行符结束。

编译并运行服务端代码：

$ g++ udp_server.cpp -o udp_server
$ ./udp_server

编译并运行客户端代码：

$ g++ udp_client.cpp -o udp_client
$ ./udp_client localhost "What is your name?"

客户端应该会收到一个从服务器返回的答案。

运行结果如下：