C++爬虫

问题描述不是很清晰，我假设你想要的是一个C++编写的网络爬虫的示例代码。这里我将提供一个简单的C++网络爬虫的示例，使用了C++11标准的功能，如std::thread和std::future来进行异步网络请求。

#include <iostream>
#include <string>
#include <thread>
#include <future>
#include <vector>
#include <regex>
 
#include <curl/curl.h>
 
std::string get_url_content(const std::string& url) {
    CURL *curl;
    CURLcode res;
    std::string readBuffer;
 
    curl = curl_easy_init();
    if(curl) {
        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, [](void *ptr, size_t size, size_t nmemb, void *stream) {
            ((std::string*)stream)->append((char*)ptr, size * nmemb);
            return size * nmemb;
        });
        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &readBuffer);
        res = curl_easy_perform(curl);
        if(res != CURLE_OK) {
            std::cerr << "curl_easy_perform() failed: " << curl_easy_strerror(res) << std::endl;
        }
        curl_easy_cleanup(curl);
    }
    return readBuffer;
}
 
std::vector<std::string> extract_urls(const std::string& html) {
    std::vector<std::string> urls;
    std::regex url_regex(R"(https?:\/\/[^\s]+)");
    std::sregex_iterator it(html.begin(), html.end(), url_regex);
    std::sregex_iterator end;
    while (it != end) {
        urls.push_back(it->str());
        ++it;
    }
    return urls;
}
 
int main() {
    std::string start_url = "http://example.com";
    std::vector<std::string> pending_urls = { start_url };
    std::vector<std::future<std::string>> futures;
 
    while (!pending_urls.empty()) {
        std::string url = pending_urls.back();
        pending_urls.pop_back();
 
        std::future<std::string> future = std::async(std::launch::async, get_url_content, url);
        futures.push_back(std::move(future));
 
        while (!futures.empty() && futures.front().wait_for(std::chrono::seconds(0)) == std::future_status::ready) {
            std::string html = futures.front().get();
            std::vector<std::string> found_urls = extract_urls(html);
            for (const std::string& found_url : found_urls) {
                bool already_visited = false;
                for (const std::string& pending_url : pending_urls) {
                    if (pending_url == found_url) {
                        already_visited = true;
                        break;
                    }
                }