编写一个客户端和服务器端C语言程序，客户端连接到服务器端后，请求一个文档，然后显示结果。

好的，我可以为您提供一个简单的示例程序来实现这个功能。以下是基于socket编程实现的客户端和服务器端C语言程序：

服务器端代码：

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

#define PORT 8080
#define BUFFER_SIZE 1024

int main(int argc, char const *argv[])
{
    int server_fd, new_socket, valread;
    struct sockaddr_in address;
    int opt = 1;
    int addrlen = sizeof(address);
    char buffer[BUFFER_SIZE] = {0};
    char *response = "Hello from server";

    // 创建socket
    if ((server_fd = socket(AF_INET, SOCK_STREAM, 0)) == 0)
    {
        perror("socket failed");
        exit(EXIT_FAILURE);
    }

    // 设置socket选项
    if (setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR | SO_REUSEPORT, &opt, sizeof(opt)))
    {
        perror("setsockopt failed");
        exit(EXIT_FAILURE);
    }

    // 绑定socket到指定端口
    address.sin_family = AF_INET;
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_port = htons(PORT);

    if (bind(server_fd, (struct sockaddr *)&address, sizeof(address)) < 0)
    {
        perror("bind failed");
        exit(EXIT_FAILURE);
    }

    // 监听socket
    if (listen(server_fd, 3) < 0)
    {
        perror("listen failed");
        exit(EXIT_FAILURE);
    }

    // 接受客户端连接并发送响应
    if ((new_socket = accept(server_fd, (struct sockaddr *)&address, (socklen_t *)&addrlen)) < 0)
    {
        perror("accept failed");
        exit(EXIT_FAILURE);
    }

    valread = read(new_socket, buffer, BUFFER_SIZE);
    printf("Received request: %s\n", buffer);

    send(new_socket, response, strlen(response), 0);
    printf("Response sent: %s\n", response);

    return 0;
}

客户端代码：

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

#define PORT 8080
#define BUFFER_SIZE 1024

int main(int argc, char const *argv[])
{
    int sock = 0, valread;
    struct sockaddr_in serv_addr;
    char *request = "GET / HTTP/1.1\r\nHost: localhost\r\n\r\n";
    char buffer[BUFFER_SIZE] = {0};

    // 创建socket
    if ((sock = socket(AF_INET, SOCK_STREAM, 0)) < 0)
    {
        printf("\n Socket creation error \n");
        return -1;
    }

    memset(&serv_addr, '0', sizeof(serv_addr));

    // 设置服务器端口和IP地址
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(PORT);

    if (inet_pton(AF_INET, "127.0.0.1", &serv_addr.sin_addr) <= 0)
    {
        printf("\nInvalid address/ Address not supported \n");
        return -1;
    }

    // 连接服务器
    if (connect(sock, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
    {
        printf("\nConnection Failed \n");
        return -1;
    }

    // 发送请求并接收响应
    send(sock, request, strlen(request), 0);
    printf("Request sent: %s\n", request);

    valread = read(sock, buffer, BUFFER_SIZE);
    printf("Response received: %s\n", buffer);

    return 0;
}

上述示例代码实现了一个简单的HTTP请求和响应，您可以修改请求和响应内容，以适应您的需求。