有幾個地方要注意的：

[]這個表示Lambda的開始，如果要加參數可以這樣：[]()后面括號里面放參數，Qt中connect中的信號，參數

1. []：里面為空，表示不使用任何參數對象的參數；

2. =：表示按值的方式進行傳遞；

3. &：表示以引用的方式進行傳遞；

4. this：表示函數體內可以使用Lambda所在類中的成員變量；

5. a：按值的方式進行傳遞，默認是不能修改的，如果要修改，需要添加mutable修飾符。

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程序結構如下：

如下代碼：

LambdaInQt.pro

QT -= guiCONFIG += c++11 console CONFIG -= app_bundle# The following define makes your compiler emit warnings if you use # any Qt feature that has been marked deprecated (the exact warnings # depend on your compiler). Please consult the documentation of the # deprecated API in order to know how to port your code away from it. DEFINES += QT_DEPRECATED_WARNINGS# You can also make your code fail to compile if it uses deprecated APIs. # In order to do so, uncomment the following line. # You can also select to disable deprecated APIs only up to a certain version of Qt. #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0SOURCES += \main.cpp# Default rules for deployment. qnx: target.path = /tmp/$${TARGET}/bin else: unix:!android: target.path = /opt/$${TARGET}/bin !isEmpty(target.path): INSTALLS += targetHEADERS += \Test.h

Test.h

#ifndef TEST_H #define TEST_H#include <QObject> #include <QTimer> #include <QDebug>class Test1{public:Test1(){}Test1(const Test1 &test){this->m_a = test.m_a;}Test1 &operator = (const Test1 &test){this->m_a = test.m_a;}int m_a; };class Test2{public:int m_a; };class MyEmit : public QObject{Q_OBJECTpublic:MyEmit() : QObject(nullptr){QTimer::singleShot(1000, [this](){this->m_test1.m_a = 10;this->m_test2.m_a = 20;});Test1 tmpTest1;tmpTest1.m_a = 100;QTimer::singleShot(1000, [=](){this->m_a = 100;this->m_test1.m_a = 100;});QTimer::singleShot(1000, [&](){this->m_a = 100;tmpTest1.m_a = 300;});int tmpa = 100;QTimer::singleShot(1000, [tmpa](){qDebug() << tmpa;});QTimer::singleShot(1000, [tmpTest1](){qDebug() << tmpTest1.m_a;});}signals:void sendSomeThing();void sendToDoSomeThing();private:int m_a;int m_b;Test1 m_test1;Test2 m_test2; };#endif // TEST_H

main.cpp

#include <QCoreApplication> #include <QDebug> #include <QTimer> #include "Test.h"int main(int argc, char *argv[]) {QCoreApplication a(argc, argv);MyEmit myEmit;QTimer::singleShot(3000, [&]{emit myEmit.sendSomeThing();});QEventLoop loop;QObject::connect(&myEmit, &MyEmit::sendSomeThing, [=](){});loop.exec();qDebug() << "over";return a.exec(); }

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