c++11 匿名函数[] [this] [&] [=]

最新推荐文章于 2025-06-21 12:57:16 发布

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最新推荐文章于 2025-06-21 12:57:16 发布 · 7.4k 阅读

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本文探讨C++11中的匿名函数特性，包括[]不截取变量、[&]截取所有变量为引用、[=]拷贝变量、[=, &foo]的混合使用以及[bar]和[this]针对特定变量的处理。这些特性为C++函数对象提供了更灵活的捕获策略。" 136273378,7947617,"大厂机试解析：二叉树计算（Python, Java, C++, JS）

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C++11 匿名函数(由[&]想到的)

最近在读别人写的C++代码时发现一些很古怪的东西：

有这样的：

         // Declare graph of factor types and build the factor structure
         std::vector<dtf::prior_t> priors;
         float tree_ms = ts::timing_ms([&]() {
            graph = InitFactorGraph(forest, priors, dags_train, sigma_unary, sigma_pw,
               levels_unary, levels_pw, feat_box_max, feat_radius);
         });
         std::cout << "Decision tree induction took " << (tree_ms/1000.0) << "s" << std::endl;

也有这样的，主函数写了一堆声明定义以后就return一个这样的东西：

  return processFrames([&](cv::Mat frame) {
    cv::Mat withoutBackground = bgHider.process(frame);
    cv::Mat eroded;
    cv::erode(withoutBackground, eroded, cv::Mat(), cv::Point(-1,-1), 3);
    cv::Mat dilated;
    cv::dilate(eroded, dilated, cv::Mat(), cv::Point(-1,-1), 5);
    //cv::Mat processed = redFilter.filter(withoutBackground);
    cv::Mat* showImage = 0;
    switch (showStage) {
      case 0: showImage = &frame; break;
      case 1: showImage = &withoutBackground; break;
      case 2: showImage = &eroded; break;
      case 3: showImage = &dilated; break;
      default: showImage = 0;
    }
    if (showImage) {
      std::ostringstream oss;
      auto millis = stopWatch.getMillisAndReset();
      oss << 1000/millis;
      cv::putText(*showImage, oss.str(),cv::Point(30,frame.rows-30), cv::FONT_HERSHEY_COMPLEX_SMALL, 0.8,