cpp-examples/lambda functions + capture lists.cpp at main · thisal-d/cpp-examples · GitHub

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#include <iostream>


int main(){
    double a{10};
    double b(20);

    /*
    auto func_error = [](){
        std::cout << a+b << std::endl;
    };
    */ // this makes error

    // capture by value
    auto func = [a,b](){
        //a++ error read only
        std::cout << a+b << std::endl;
    };

    func(); //-> 30
    a++;
    b++;
    func(); // still its 30

    // capture by reference
    auto func2 = [&a,&b](){
        std::cout << a+b << std::endl;
    };
    func2();// -> 32
    a++;
    b++;
    func2(); // -> 34


    int d = 100;
    //capture all by value
    auto func3 = [=](){
        std::cout << d  <<  std::endl;
    };


    //capture all by reference
    auto func4 = [&](){
        std::cout << d++ << std::endl;
    };


}