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
#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;
}