C++11之lambda表达式应用

时间:2022-05-03 18:43:26

 

应用

foreach语句中

#include <time.h> #include <algorithm> using namespace std; void func(int i) { cout<<i<<endl; } int main(int argc, char *argv[]) { list<int> li; srand(time(NULL)); for(int i=0;i <10; i++) { li.push_back(rand()%100); } for_each(li.begin(),li.end(),func); for_each(li.begin(),li.end(),[](int i){cout<<i<<endl;});
  //!传函数指针的地方可以用lanbda表达式替代。   return 0; }

 

sort()/list::sort()

#include <iostream> #include <vector> #include <list> #include <stdlib.h> #include <time.h> #include <algorithm> #include <functional> using namespace std; bool Compare(int i, int j) { return i<j; } int main(int argc, char *argv[]) { vector<int> vi; srand(time(NULL)); for(int i=0;i <10; i++) { vi.push_back(rand()%100); } // sort(vi.begin(),vi.end(),Compare); sort(vi.begin(),vi.end(),[](int x, int y){ return x<y;}); for_each(vi.begin(),vi.end(),[](int i){cout<<i<<endl;}); return 0;

 

 

Qt中信号槽机制

C++11之lambda表达式应用

 

#include "mainwindow.h" MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) {   this->setGeometry(600,400,400,200);   _dial = new QDial(this);   _dial->setRange(0,100);   _dial->setGeometry(50,50,100,100);   _dial->setAutoFillBackground(true);   _pBar = new QProgressBar(this);   _pBar->setGeometry(250,40,20,120);   _pBar->setMinimum(0);   _pBar->setMaximum(100);   _pBar->setOrientation(Qt::Vertical);   //connect(_dial,SIGNAL(valueChanged(int)),   _pBar,SLOT(setValue(int)));   //QObject::connect(const QObject *sender,PointerToMemberFunction signal,Functor functor)
    connect(_dial,&QDial::valueChanged,[&](int v){_pBar->setValue(v);}); 
    //!可以使用lambda表达式替代槽函数
}

MainWindow::
~MainWindow() { }

 

 

 lambda表达式与仿函数

#include <iostream> using namespace std; class Tax { 
public:   Tax(
float r, float b):_rate(r),_base(b){}   float operator()(float money)   {     return (money-_base)*_rate;   } private:   float _rate;   float _base; };

int main(int argc, char *argv[]) {   // Tax high(0.40,30000);   // Tax middle(0.25,20000);   // Tax low(0.12,10000);   // cout<<"大于 3w 的税:"<<high(37500)<<endl;   // cout<<"大于 2w 的税:"<<middle(27500)<<endl;   float rate = 0.40;   float base = 30000;   auto high = [&](float money){return (money-base)*rate;};   cout<<"大于 3w 的税:"<<high(37500)<<endl;   return 0; }