How do C++ functions handle DNS queries in network programming?

C The standard library provides functions to handle DNS queries in network programming: gethostbyname(): Find host information based on the host name. gethostbyaddr(): Find host information based on IP address. dns_lookup(): Asynchronously resolve DNS.

C function DNS query processing in network programming

In network programming, the Domain Name System (DNS) is crucial for resolving domain names into IP addresses important. The C standard library provides powerful functions to simplify this process.

Function introduction

The functions used for DNS query in the C standard library include:

• gethostbyname(): Find the host based on the host name information.
• gethostbyaddr(): Find host information based on IP address.
• dns_lookup(): Asynchronously resolve DNS based on hostname or IP address.

Practical case

Suppose we want to obtain the IP address of www.google.com and display the results. Here is a code example using gethostbyname():

#include <netdb.h>
#include <iostream>

int main() {
  // 获取主机名
  std::string hostname = "www.google.com";

  // 获取主机信息
  struct hostent *host = gethostbyname(hostname.c_str());

  // 检查是否有错误
  if (!host) {
    std::cerr << "gethostbyname() failed" << std::endl;
    return EXIT_FAILURE;
  }

  // 输出 IP 地址
  std::cout << "IP 地址：" << host->h_addr_list[0] << std::endl;

  return EXIT_SUCCESS;
}

The above is the detailed content of How do C++ functions handle DNS queries in network programming?. For more information, please follow other related articles on the PHP Chinese website!