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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

 1 #include <algorithm>
 2 #include <array>
 3 #include <cstdint>
 4 #include <iostream>
 5 
 6 int main()
 7 {
 8     using MyArray = std::array<uint32_t, 5>;
 9     MyArray myArray{ 1, 2, 3, 4, 5 };
10 
11     std::for_each(myArray.cbegin(),
12         myArray.cend(),
13         [](auto&& number) {
14             std::cout << number << std::endl;
15         });
16 
17     return 0;
18 }
View Code

Referencing a Closure in a Variable

 1 #include <algorithm>
 2 #include <array>
 3 #include <cstdint>
 4 #include <iostream>
 5 #include <typeinfo>
 6 
 7 int main()
 8 {
 9     using MyArray = std::array<uint32_t, 5>;
10     MyArray myArray{ 1, 2, 3, 4, 5 };
11 
12     auto myClosure = [](auto&& number) {
13             std::cout << number << std::endl;
14         };
15     std::cout << typeid(myClosure).name() << std::endl;
16 
17     std::for_each(myArray.begin(),
18         myArray.end(),
19         myClosure);
20 
21     return 0;
22 }
View Code

下面是一些关于闭包的使用：

１．Passing a Closure into a Function　

 1 #include <algorithm>
 2 #include <array>
 3 #include <cstdint>
 4 #include <functional>
 5 #include <iostream>
 6 #include <typeinfo>
 7 
 8 using MyArray = std::array<uint32_t, 5>;
 9 
10 void PrintArray(const std::function<void(MyArray::value_type)>& myFunction)
11 {
12     MyArray myArray{ 1, 2, 3, 4, 5 };
13 
14     std::for_each(myArray.begin(),
15         myArray.end(),
16         myFunction);
17 }
18 
19 int main()
20 {
21     auto myClosure = [](auto&& number) {
22             std::cout << number << std::endl;
23         };
24     std::cout << typeid(myClosure).name() << std::endl;
25     PrintArray(myClosure);
26     return 0;
27 }
View Code

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

 1 #include <algorithm>
 2 #include <array>
 3 #include <cstdint>
 4 #include <functional>
 5 #include <iostream>
 6 #include <typeinfo>
 7 #include <vector>
 8 
 9 using MyArray = std::array<uint32_t, 5>;
10 using MyVector = std::vector<MyArray::value_type>;
11 
12 void PrintArray(const std::function<void(MyArray::value_type)>& myFunction)
13 {
14     MyArray myArray{ 1, 2, 3, 4, 5 };
15 
16     std::for_each(myArray.begin(),
17         myArray.end(),
18         myFunction);
19 }
20 
21 int main()
22 {
23     MyVector myCopy;
24     auto myClosure = [&myCopy](auto&& number) {
25             std::cout << number << std::endl;
26             myCopy.push_back(number);
27         };
28     std::cout << typeid(myClosure).name() << std::endl;
29 
30     PrintArray(myClosure);
31 
32     std::cout << std::endl << "My Copy: " << std::endl;
33     std::for_each(myCopy.cbegin(),
34         myCopy.cend(),
35         [](auto&& number){
36             std::cout << number << std::endl;
37         });
38 
39     return 0;
40 }
View Code

３．C++11 Compatible Lambda Function

 1 #include <algorithm>
 2 #include <array>
 3 #include <cstdint>
 4 #include <functional>
 5 #include <iostream>
 6 #include <typeinfo>
 7 #include <vector>
 8 
 9 using MyArray = std::array<uint32_t, 5>;
10 using MyVector = std::vector<MyArray::value_type>;
11 
12 void PrintArray(const std::function<void(MyArray::value_type)>& myFunction)
13 {
14     MyArray myArray{ 1, 2, 3, 4, 5 };
15 
16     std::for_each(myArray.begin(),
17         myArray.end(),
18         myFunction);
19 }
20 
21 int main()
22 {
23     MyVector myCopy;
24     auto myClosure = [&myCopy](const MyArray::value_type&number) {
25             std::cout << number << std::endl;
26             myCopy.push_back(number);
27         };
28     std::cout << typeid(myClosure).name() << std::endl;
29 
30     PrintArray(myClosure);
31 
32     std::cout << std::endl << "My Copy: " << std::endl;
33     std::for_each(myCopy.cbegin(),
34         myCopy.cend(),
35         [](const MyVector::value_type&number){
36             std::cout << number << std::endl;
37         });
38 
39     return 0;
40 }
View Code

４．keyward mutable

 

posted on 2016-11-06 16:56  Lauen_1  阅读(119)  评论(0)  编辑  收藏  举报

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