Qt lambda函数

### Qt Lambda Function Usage and Examples In the context of Qt, lambda functions provide a convenient way to define inline functions at the location where they are called. These anonymous functions can capture variables from their surrounding scope, making them particularly useful for connecting signals and slots or executing tasks within threads. #### Connecting Signals and Slots with Lambdas Lambda expressions offer an elegant alternative to traditional signal-slot connections by allowing more flexible parameter handling: ```cpp // Example of using lambdas for signal-slot connection connect(button, &QPushButton::clicked, [=]() { qDebug() << "Button clicked!"; }); ``` This code snippet demonstrates how a button click event triggers a debug message without needing a separate slot method[^1]. #### Using Lambdas with QThreads For thread management, combining `QThread` with lambda expressions simplifies task execution while maintaining readability: ```cpp auto worker = new QObject; worker->moveToThread(&thread); connect(&thread, &QThread::started, [worker]() { // Perform time-consuming operations here }); connect(worker, &QObject::destroyed, [&thread]() { thread.quit(); thread.wait(); }); thread.start(); ``` Here, when the thread starts, it executes the specified operation inside the lambda expression. Once finished, cleanup actions ensure proper resource release. #### Capturing Variables in Lambdas Lambdas support capturing local variables either by value (`=`) or reference (`&`). This feature is crucial for accessing external data structures during asynchronous processing: ```cpp int count = 0; connect(timer, &QTimer::timeout, [count]() mutable { ++count; // Increment captured variable qDebug() << "Count:" << count; }); ``` Note that modifying captured values requires declaring the lambda as `mutable`.