netdb(找不到 Netinet 和 netdb)

在C++中,netinet和netdb是C語言中的網絡庫,在C++中可以使用<sys/socket.h>和<netdb.h>頭文件來包含這些庫。

以下是一個簡單的示例代碼,演示如何使用<sys/socket.h>和<netdb.h>頭文件來使用網絡庫:

#include <iostream>#include <sys/socket.h>#include <netdb.h>int main() {// 創建一個socketint serverSocket = socket(AF_INET, SOCK_STREAM, 0);if (serverSocket == -1) {std::cout << "Error creating socket." << std::endl;return 1;}// 獲取IP地址struct hostent* host = gethostbyname("www.example.com");if (host == nullptr) {std::cout << "Error retrieving IP address." << std::endl;return 1;}struct in_addr** addressList = (struct in_addr**)host->h_addr_list;std::string ipAddress = inet_ntoa(*addressList[0]);std::cout << "IP address: " << ipAddress << std::endl;// 連接到服務器struct sockaddr_in serverAddress;serverAddress.sin_family = AF_INET;serverAddress.sin_port = htons(80);if (inet_pton(AF_INET, ipAddress.c_str(), &(serverAddress.sin_addr)) <= 0) {std::cout << "Invalid IP address." << std::endl;return 1;}if (connect(serverSocket, (struct sockaddr*)&serverAddress, sizeof(serverAddress)) < 0) {std::cout << "Error connecting to server." << std::endl;return 1;}// 發送數據std::string message = "GET / HTTP/1.1\r\nHost: www.example.com\r\n\r\n";if (send(serverSocket, message.c_str(), message.length(), 0) < 0) {std::cout << "Error sending data." << std::endl;return 1;}// 接收服務器響應char buffer[4096];std::string response;while (true) {memset(buffer, 0, sizeof(buffer));int bytesRead = recv(serverSocket, buffer, sizeof(buffer) - 1, 0);if (bytesRead <= 0) {break;}response += buffer;}// 關閉socketclose(serverSocket);// 打印服務器響應std::cout << response << std::endl;return 0;}

這個示例代碼創建一個socket對象,然后使用gethostbyname函數獲取www.example.com的IP地址,然后使用connect函數連接到服務器,然后發送HTTP請求并接收服務器的響應,最后關閉socket并打印響應。

注意,這只是一個簡單的示例,實際使用網絡庫可能需要更多的錯誤處理和邏輯。