\n 1\r\n 2\r\n 3\r\n 4\r\n 5\r\n 6\r\n 7\r\n 8\r\n 9\r\n10\r\n11\r\n12\r\n13\r\n14\r\n15\r\n16\r\n17\r\n18\r\n19\r\n20\r\n21\r\n22\r\n23\r\n24\r\n25\r\n26\r\n27\r\n28\r\n29\r\n30\r\n31\r\n32\r\n33\r\n34\r\n35\r\n36\r\n37\r\n38\r\n39\r\n40\r\n41\r\n42\r\n43\r\n44<\/pre>\n<\/td>\n\n\/\/ algorithm.cpp<\/span>\r\n\r\n#include <algorithm><\/span>\r\n#include <iostream><\/span>\r\n#include <numeric><\/span>\r\n#include <vector><\/span>\r\n\r\nint<\/span> main(){\r\n\r\n std::cout << std::endl;\r\n\r\n std::vector<int<\/span>> myVec{1,2,3,4,5,6,7,8,9};\r\n\r\n std::cout << \"original: \"<\/span>;\r\n for<\/span> (auto<\/span> a: myVec) { std::cout << a << \" \"<\/span>;}\r\n\r\n std::cout << \"\\n\\n\"<\/span>;\r\n \r\n std::transform(myVec.begin(),myVec.end(),myVec.begin(), [](int<\/span> i){ return<\/span> i*i; });\r\n\r\n std::cout << \"std::transform: \"<\/span>;\r\n for<\/span> (auto<\/span> a: myVec) { std::cout << a << \" \"<\/span>;}\r\n \r\n std::cout << \"\\n\\n\"<\/span>;\r\n \r\n myVec={1,2,3,4,5,6,7,8,9};\r\n \r\n auto<\/span> logicalEnd= std::remove_if(myVec.begin(),myVec.end(), [](int<\/span> i){ return<\/span> !((i < 3) or (i > 8)); });\r\n myVec.erase(logicalEnd,myVec.end());\r\n \r\n std::cout << \"std::remove_if: \"<\/span>;\r\n for<\/span> (auto<\/span> a: myVec) { std::cout << a << \" \"<\/span>;}\r\n \r\n std::cout << \"\\n\\n\"<\/span>;\r\n \r\n myVec={1,2,3,4,5,6,7,8,9};\r\n \r\n std::cout << \"std::accumulate: \"<\/span>;\r\n auto<\/span> fak= std::accumulate(myVec.begin(),myVec.end(),1,[](int<\/span> fir, int<\/span> sec){ return<\/span> fir * sec; });\r\n std::cout << \"fak(10): \"<\/span> << fak << std::endl;\r\n \r\n std::cout << std::endl;\r\n\r\n}\r\n<\/pre>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n <\/p>\n I fully intentionally used lambda functions in the example. Although the algorithm can accept all, that behaves like a function. But lambda functions should be your first choice. C++ has supported lambda functions since C++11. That will also hold for the three additional features from C++11 that I used in the example: automatic type deduction with auto<\/span> (lines 22, 32, and 39), unified initialization (lines 12, 26, and 36), and the range-based for-loop (line 22 and 32).<\/p>\nThe program should be self-explanatory in combination with the output. I will only mention one specialty of the STL algorithm in line 28. The std::remove_if<\/span> does not remove – like all generic algorithms of the STL – the elements from the container. std::remove_if<\/span> returns the logical end of the new container. This logical end is used by the myVec.erase<\/span> method, which shortens the container to its correct length.<\/p>\nThe method erase<\/span> is not a generic algorithm of the STL but a method of std::vector.<\/span> <\/strong><\/p>\n![\"algorithm\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2017\/01\/algorithm.png\") <\/h3>\nWhat’s next?<\/h2>\n
I will write in the next post<\/a> about Technical Report 1 from 2005. I’m particularly interested in the two functions std::bind<\/span> and std::function,<\/span> which introduce a new technique in C++: partial function application. Partial function application is similar to the functional technique currying, also called sch\u00f6nfinkeln. Sch\u00f6nfinkeln, that sounds extremely promising.<\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" C++ is not a functional programming language, but you can program in a functional style. What are the functional features of C++? I will answer this question for C++98.<\/p>\n","protected":false},"author":21,"featured_media":5120,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[365],"tags":[],"class_list":["post-5126","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-functional"],"_links":{"self":[{"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/posts\/5126","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/users\/21"}],"replies":[{"embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/comments?post=5126"}],"version-history":[{"count":0,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/posts\/5126\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/media\/5120"}],"wp:attachment":[{"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/media?parent=5126"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/categories?post=5126"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.modernescpp.com\/index.php\/wp-json\/wp\/v2\/tags?post=5126"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}} | | ![\"timeline.FunktionalEng\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2017\/01\/timeline.FunktionalEng.png\")
<\/p>\n![\"timeline.Funktional98Eng\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2017\/01\/timeline.Funktional98Eng.png\")
<\/p>\n![\"TemplateInstanziierungEng\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2017\/01\/TemplateInstanziierungEng.png\")
<\/p>\n\n![\"factorial\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2017\/01\/factorial.png\")
<\/p>\n![\"factorialInstanziation\"](\"https:\/\/www.modernescpp.com\/wp-content\/uploads\/2017\/01\/factorialInstanziation.png\")
<\/p>\n