c语言中利用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。需要客户端和服务端的两个代码

以下是一个简单的示例，包括客户端和服务端的代码。服务端将从文本文件中读取问题和答案，客户端将向服务端发送问题并接收答案。

服务端代码（server.c）：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define BUF_SIZE 1024
#define FILE_NAME "qa.txt"

void error(const char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr, cli_addr;
    socklen_t clilen;
    char buffer[BUF_SIZE];
    FILE *fp;

    if (argc < 2) {
        fprintf(stderr, "Usage: %s port\n", argv[0]);
        exit(1);
    }

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");

    memset(&serv_addr, 0, sizeof(serv_addr));
    portno = atoi(argv[1]);
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    serv_addr.sin_port = htons(portno);

    if (bind(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
        error("ERROR on binding");

    clilen = sizeof(cli_addr);

    fp = fopen(FILE_NAME, "r");
    if (fp == NULL)
        error("ERROR opening file");

    while (1) {
        memset(buffer, 0, BUF_SIZE);

        n = recvfrom(sockfd, buffer, BUF_SIZE - 1, 0,
            (struct sockaddr *)&cli_addr, &clilen);
        if (n < 0)
            error("ERROR receiving from socket");

        buffer[n] = '\0';

        char *ptr;
        ptr = strstr(buffer, "?");
        if (ptr != NULL) {
            *ptr = '\0';
            ptr++;
            printf("Question: %s\n", buffer);

            int found = 0;
            char line[BUF_SIZE];
            while (fgets(line, BUF_SIZE, fp) != NULL) {
                if (strncmp(line, buffer, strlen(buffer)) == 0) {
                    found = 1;
                    break;
                }
            }

            if (found) {
                char *answer = strtok(line, "\t");
                answer = strtok(NULL, "\n");
                printf("Answer: %s\n", answer);

                n = sendto(sockfd, answer, strlen(answer), 0,
                    (struct sockaddr *)&cli_addr, clilen);
                if (n < 0)
                    error("ERROR sending to socket");
            } else {
                printf("Answer not found.\n");

                char *not_found = "I don't know.";
                n = sendto(sockfd, not_found, strlen(not_found), 0,
                    (struct sockaddr *)&cli_addr, clilen);
                if (n < 0)
                    error("ERROR sending to socket");
            }

            rewind(fp);
        }
    }

    fclose(fp);
    close(sockfd);

    return 0;
}

客户端代码（client.c）：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#define BUF_SIZE 1024

void error(const char *msg)
{
    perror(msg);
    exit(1);
}

int main(int argc, char *argv[])
{
    int sockfd, portno, n;
    struct sockaddr_in serv_addr;
    char buffer[BUF_SIZE];

    if (argc < 3) {
        fprintf(stderr, "Usage: %s hostname port\n", argv[0]);
        exit(1);
    }

    sockfd = socket(AF_INET, SOCK_DGRAM, 0);
    if (sockfd < 0)
        error("ERROR opening socket");

    memset(&serv_addr, 0, sizeof(serv_addr));
    portno = atoi(argv[2]);
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(portno);

    if (inet_pton(AF_INET, argv[1], &serv_addr.sin_addr) <= 0)
        error("ERROR invalid address");

    while (1) {
        printf("Question: ");
        memset(buffer, 0, BUF_SIZE);
        fgets(buffer, BUF_SIZE - 1, stdin);
        if (buffer[strlen(buffer) - 1] == '\n')
            buffer[strlen(buffer) - 1] = '\0';

        n = sendto(sockfd, buffer, strlen(buffer), 0,
            (struct sockaddr *)&serv_addr, sizeof(serv_addr));
        if (n < 0)
            error("ERROR sending to socket");

        memset(buffer, 0, BUF_SIZE);

        n = recvfrom(sockfd, buffer, BUF_SIZE - 1, 0, NULL, NULL);
        if (n < 0)
            error("ERROR receiving from socket");

        buffer[n] = '\0';

        printf("Answer: %s\n", buffer);
    }

    close(sockfd);

    return 0;
}

注意：这只是一个简单的示例，并不具有完整性和健壮性。实际应用中需要考虑更多的因素，例如文件读取和网络通信的错误处理、并发访问等。