2-6 Working with Lambdas

在Ｃ++中使用匿名函数，格式如下：[] () {};

Using a Lambda to Print array Values

 #include <algorithm>
 #include <array>
 #include <cstdint>
 #include <iostream>

 int main()
 {
     using MyArray = std::array<uint32_t, >;
     MyArray myArray{ , , , ,  };

     std::for_each(myArray.cbegin(),
         myArray.cend(),
         [](auto&& number) {
             std::cout << number << std::endl;
         });

     return ;
 }

Referencing a Closure in a Variable

 #include <algorithm>
 #include <array>
 #include <cstdint>
 #include <iostream>
 #include <typeinfo>

 int main()
 {
     using MyArray = std::array<uint32_t, >;
     MyArray myArray{ , , , ,  };

     auto myClosure = [](auto&& number) {
             std::cout << number << std::endl;
         };
     std::cout << typeid(myClosure).name() << std::endl;

     std::for_each(myArray.begin(),
         myArray.end(),
         myClosure);

     return ;
 }

下面是一些关于闭包的使用：

１．Passing a Closure into a Function　

 #include <algorithm>
 #include <array>
 #include <cstdint>
 #include <functional>
 #include <iostream>
 #include <typeinfo>

 using MyArray = std::array<uint32_t, >;

 void PrintArray(const std::function<void(MyArray::value_type)>& myFunction)
 {
     MyArray myArray{ , , , ,  };

     std::for_each(myArray.begin(),
         myArray.end(),
         myFunction);
 }

 int main()
 {
     auto myClosure = [](auto&& number) {
             std::cout << number << std::endl;
         };
     std::cout << typeid(myClosure).name() << std::endl;
     PrintArray(myClosure);
     return ;
 }

２．Copy an array into a vector through a lambda using the capture block

 #include <algorithm>
 #include <array>
 #include <cstdint>
 #include <functional>
 #include <iostream>
 #include <typeinfo>
 #include <vector>

 using MyArray = std::array<uint32_t, >;
 using MyVector = std::vector<MyArray::value_type>;

 void PrintArray(const std::function<void(MyArray::value_type)>& myFunction)
 {
     MyArray myArray{ , , , ,  };

     std::for_each(myArray.begin(),
         myArray.end(),
         myFunction);
 }

 int main()
 {
     MyVector myCopy;
     auto myClosure = [&myCopy](auto&& number) {
             std::cout << number << std::endl;
             myCopy.push_back(number);
         };
     std::cout << typeid(myClosure).name() << std::endl;

     PrintArray(myClosure);

     std::cout << std::endl << "My Copy: " << std::endl;
     std::for_each(myCopy.cbegin(),
         myCopy.cend(),
         [](auto&& number){
             std::cout << number << std::endl;
         });

     return ;
 }

３．C++11 Compatible Lambda Function

 #include <algorithm>
 #include <array>
 #include <cstdint>
 #include <functional>
 #include <iostream>
 #include <typeinfo>
 #include <vector>

 using MyArray = std::array<uint32_t, >;
 using MyVector = std::vector<MyArray::value_type>;

 void PrintArray(const std::function<void(MyArray::value_type)>& myFunction)
 {
     MyArray myArray{ , , , ,  };

     std::for_each(myArray.begin(),
         myArray.end(),
         myFunction);
 }

 int main()
 {
     MyVector myCopy;
     auto myClosure = [&myCopy](const MyArray::value_type&number) {
             std::cout << number << std::endl;
             myCopy.push_back(number);
         };
     std::cout << typeid(myClosure).name() << std::endl;

     PrintArray(myClosure);

     std::cout << std::endl << "My Copy: " << std::endl;
     std::for_each(myCopy.cbegin(),
         myCopy.cend(),
         [](const MyVector::value_type&number){
             std::cout << number << std::endl;
         });

     return ;
 }

４．keyward mutable