• [capture clause](parameters) -> return-type {body}

#include <iostream>
#include <vector>
#include <algorithm>

int main(int argc, char *argv[])
{
	std::vector<int> v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

	auto f = [](int x){if(x%2 == 0) std::cout<<x<<std::endl;};

	for_each(v.begin(), v.end(), [](int x){if(x%2 == 0) std::cout<<x<<std::endl;});

	for_each(v.begin(), v.end(), f);

	return 0;
}
		

#include <iostream>
#include <vector>
#include <algorithm>

int main(int argc, char *argv[])
{
	std::vector<int> v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

	for_each(v.begin(), v.end(), [](int &x){if(x%2 == 0) x *= 10;});

	for_each(v.begin(), v.end(), [](int x) {std::cout<<x<<std::endl;});

	return 0;
}
			

#include <iostream>
#include <vector>
#include <algorithm>

int main(int argc, char *argv[])
{
	std::vector<int> v = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

	int num = 3;

	//capture by value
	std::cout<<"Capture by Value: "<<std::endl;
	for_each(v.begin(), v.end(), [=](int &x){if(x%num == 0) std::cout<<num<<std::endl;});

	//capture by reference
	std::cout<<"Capture by Reference: "<<std::endl;
	for_each(v.begin(), v.end(), [&](int &x){if(x%num == 0) {num++; std::cout<<num<<std::endl;}});

	return 0;
}
			

• [=], capture all of the variables from the enclosing scope by value
• [&], capture all of the variables from the enclosing scope by reference

//Rectangle.h
#ifndef RECTANGLE_H
#define RECTANGLE_H
class Rectangle
{
	private:
		double width;
		double length;
	public:
		//constructor
		Rectangle(double w, double l):width(w), length(l){}

		//accessor
		double getWidth() const {return width;}
		double getLength() const {return length;}
		double getArea() const {return width*length;}

		void display()
		{
			auto f = [this](int i){if (i>10) std::cout<<getArea()<<std::endl;};
			f(20);
		}
};
#endif
			

• [this], capture all of the data members of the enclosing class
• Using C++ Lambdas

#include <iostream>
#include "Rectangle.h"

int main(int argc, char *argv[])
{
	Rectangle r(5, 10);

	double minWidth = 2;
	double minLength =5;

	auto f = [minWidth, &minLength](const Rectangle &r){std::cout<<minWidth<<std::endl; if(r.getLength() > minLength) minLength = r.getLength();};

	f(r);

	std::cout<<"Min Width: "<<minWidth<<std::endl;
	std::cout<<"Min Length: "<<minLength<<std::endl;

	return 0;
}
			

• [minWidth, &minLength], minWidth pass by value, minLength pass by reference

#include <iostream>
#include <vector>
#include <algorithm>

int main(int argc, char *argv[])
{
	std::vector<int> v = {1, 2, 3, 4};

	for_each(v.begin(), v.end(), [](int i){std::cout<<i<<std::endl;});

	return 0;
}
			

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• drdobbs.com