{"id":73,"date":"2021-05-24T23:07:31","date_gmt":"2021-05-24T15:07:31","guid":{"rendered":"https:\/\/blog.cauchyschwarz.com\/?p=73"},"modified":"2021-05-25T08:45:17","modified_gmt":"2021-05-25T00:45:17","slug":"%e6%b7%b1%e5%85%a5%e5%ba%94%e7%94%a8c11%e7%ac%94%e8%ae%b0-%e7%ac%ac3%e7%ab%a0","status":"publish","type":"post","link":"https:\/\/blog.cauchyschwarz.com\/?p=73","title":{"rendered":"\u6df1\u5165\u5e94\u7528C++11\u7b14\u8bb0 \u7b2c3\u7ae0"},"content":{"rendered":"\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_85 ez-toc-wrap-right counter-hierarchy ez-toc-counter ez-toc-grey ez-toc-container-direction\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<label for=\"ez-toc-cssicon-toggle-item-6a2cc11cbede5\" class=\"ez-toc-cssicon-toggle-label\"><span class=\"\"><span class=\"eztoc-hide\" style=\"display:none;\">Toggle<\/span><span class=\"ez-toc-icon-toggle-span\"><svg style=\"fill: #999;color:#999\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" class=\"list-377408\" width=\"20px\" height=\"20px\" viewBox=\"0 0 24 24\" fill=\"none\"><path d=\"M6 6H4v2h2V6zm14 0H8v2h12V6zM4 11h2v2H4v-2zm16 0H8v2h12v-2zM4 16h2v2H4v-2zm16 0H8v2h12v-2z\" fill=\"currentColor\"><\/path><\/svg><svg style=\"fill: #999;color:#999\" class=\"arrow-unsorted-368013\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\" width=\"10px\" height=\"10px\" viewBox=\"0 0 24 24\" version=\"1.2\" baseProfile=\"tiny\"><path d=\"M18.2 9.3l-6.2-6.3-6.2 6.3c-.2.2-.3.4-.3.7s.1.5.3.7c.2.2.4.3.7.3h11c.3 0 .5-.1.7-.3.2-.2.3-.5.3-.7s-.1-.5-.3-.7zM5.8 14.7l6.2 6.3 6.2-6.3c.2-.2.3-.5.3-.7s-.1-.5-.3-.7c-.2-.2-.4-.3-.7-.3h-11c-.3 0-.5.1-.7.3-.2.2-.3.5-.3.7s.1.5.3.7z\"\/><\/svg><\/span><\/span><\/label><input type=\"checkbox\"  id=\"ez-toc-cssicon-toggle-item-6a2cc11cbede5\" checked aria-label=\"Toggle\" \/><nav><ul class='ez-toc-list ez-toc-list-level-1 ' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E4%BD%BF%E7%94%A8C11%E6%B6%88%E9%99%A4%E9%87%8D%E5%A4%8D%EF%BC%8C%E6%8F%90%E9%AB%98%E4%BB%A3%E7%A0%81%E8%B4%A8%E9%87%8F\" >\u4f7f\u7528C++11\u6d88\u9664\u91cd\u590d\uff0c\u63d0\u9ad8\u4ee3\u7801\u8d28\u91cf<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E7%B1%BB%E5%9E%8B%E8%90%83%E5%8F%96type_traits\" >\u7c7b\u578b\u8403\u53d6(type_traits)<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#integral_constant\" >integral_constant<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E7%B1%BB%E5%9E%8B%E5%88%A4%E6%96%AD%E7%9A%84type_traits\" >\u7c7b\u578b\u5224\u65ad\u7684type_traits<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E5%88%A4%E6%96%AD%E4%B8%A4%E4%B8%AA%E7%B1%BB%E5%9E%8B%E4%B9%8B%E9%97%B4%E7%9A%84%E5%85%B3%E7%B3%BB\" >\u5224\u65ad\u4e24\u4e2a\u7c7b\u578b\u4e4b\u95f4\u7684\u5173\u7cfb<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E7%B1%BB%E5%9E%8B%E8%BD%AC%E6%8D%A2\" >\u7c7b\u578b\u8f6c\u6362<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#conditional\" >conditional<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E8%8E%B7%E5%8F%96%E5%8F%AF%E8%B0%83%E7%94%A8%E5%AF%B9%E8%B1%A1%E8%BF%94%E5%9B%9E%E7%B1%BB%E5%9E%8B\" >\u83b7\u53d6\u53ef\u8c03\u7528\u5bf9\u8c61\u8fd4\u56de\u7c7b\u578b<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#enable_if%E4%B8%8ESFINAE\" >enable_if\u4e0eSFINAE<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E5%8F%AF%E5%8F%98%E5%8F%82%E6%95%B0%E6%A8%A1%E6%9D%BF\" >\u53ef\u53d8\u53c2\u6570\u6a21\u677f<\/a><ul class='ez-toc-list-level-4' ><li class='ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E5%8F%AF%E5%8F%98%E5%8F%82%E6%95%B0%E6%A8%A1%E6%9D%BF%E5%87%BD%E6%95%B0\" >\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u51fd\u6570<\/a><ul class='ez-toc-list-level-5' ><li class='ez-toc-heading-level-5'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E9%80%9A%E8%BF%87%E9%80%92%E5%BD%92%E5%B1%95%E5%BC%80%E5%8F%82%E6%95%B0%E5%8C%85\" >\u901a\u8fc7\u9012\u5f52\u5c55\u5f00\u53c2\u6570\u5305<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-5'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E9%80%9A%E8%BF%87parameter_pack_expansion%E5%B1%95%E5%BC%80%E5%8F%82%E6%95%B0%E5%8C%85\" >\u901a\u8fc7parameter pack expansion\u5c55\u5f00\u53c2\u6570\u5305<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-4'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E5%8F%AF%E5%8F%98%E5%8F%82%E6%95%B0%E6%A8%A1%E6%9D%BF%E7%B1%BB\" >\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/blog.cauchyschwarz.com\/?p=73\/#%E5%8F%AF%E5%8F%98%E5%8F%82%E6%95%B0%E6%A8%A1%E6%9D%BF%E5%92%8Ctype_traits%E7%9A%84%E7%BB%BC%E5%90%88%E5%BA%94%E7%94%A8\" >\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u548ctype_traits\u7684\u7efc\u5408\u5e94\u7528<\/a><\/li><\/ul><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E4%BD%BF%E7%94%A8C11%E6%B6%88%E9%99%A4%E9%87%8D%E5%A4%8D%EF%BC%8C%E6%8F%90%E9%AB%98%E4%BB%A3%E7%A0%81%E8%B4%A8%E9%87%8F\"><\/span>\u4f7f\u7528C++11\u6d88\u9664\u91cd\u590d\uff0c\u63d0\u9ad8\u4ee3\u7801\u8d28\u91cf<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">\u901a\u8fc7\u5b9e\u73b0\u51fd\u6570\u548c\u7c7b\u6211\u4eec\u53ef\u4ee5\u91cd\u7528\u4ee3\u7801\uff0c\u800c\u901a\u8fc7\u5199\u6a21\u677f\u5219\u53ef\u4ee5\u5199\u4e00\u6b21\u4ee3\u7801\u751f\u6210\u591a\u4e2a\u5177\u6709\u76f8\u4f3c\u884c\u4e3a\u7684\u51fd\u6570\u548c\u7c7b\uff0c\u8fdb\u4e00\u6b65\u7cbe\u7b80\u4e86\u4ee3\u7801\u3002C++11\u63d0\u4f9b\u4e86\u66f4\u591a\u7684\u5199\u6a21\u677f\u7684\u5de5\u5177\u7c7b\/\u51fd\u6570\uff0c\u65b9\u4fbf\u6211\u4eec\u5728\u6b64\u57fa\u7840\u4e0a\u5199\u51fa\u597d\u7528\u7684\u6a21\u677f\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E7%B1%BB%E5%9E%8B%E8%90%83%E5%8F%96type_traits\"><\/span>\u7c7b\u578b\u8403\u53d6(type_traits)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">C++11\u63d0\u4f9b\u4e86\u4e00\u4e9b\u6a21\u677f\u4ee5\u5728\u7f16\u8bd1\u65f6\u83b7\u5f97\u7c7b\u578b\u76f8\u5173\u4fe1\u606f\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"integral_constant\"><\/span>integral_constant<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e9b\u6a21\u677f\u4e2d\u7684\u5f88\u591a\u90fd\u662f\u4ece<code>std::integral_constant<\/code>\u6d3e\u751f\u800c\u6765\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>template &lt;class T, T v&gt;\nstruct integral_constant {\n  static const T value = v;\n  typedef T value_type;\n  typedef integral_constant&lt;T, v&gt; type;\n  operator value_type() { return value; }\n};<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u7ee7\u627f\u81ea<code>integral_constant<\/code>\u6a21\u677f\u7c7b\u7684\u7c7b\u53ef\u4ee5\u901a\u8fc7\u8bbf\u95ee<code>value<\/code>\uff0c\u83b7\u53d6\u9884\u5148\u5b58\u5728<code>integral_constatant<\/code>\u6a21\u677f\u7c7b\u4e2d\u7684\u503c\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E7%B1%BB%E5%9E%8B%E5%88%A4%E6%96%AD%E7%9A%84type_traits\"><\/span>\u7c7b\u578b\u5224\u65ad\u7684type_traits<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td>traits\u7c7b\u578b<\/td><td>\u8bf4\u660e<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_void;<\/td><td>\u5224\u65adT\u662f\u5426\u662fvoid\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_floating_point;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u6d6e\u70b9\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_array;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u6570\u7ec4\u4fee\u6539\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_pointer;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u6307\u9488\u7c7b\u578b(\u5305\u62ec\u51fd\u6570\u6307\u9488\uff0c\u4e0d\u5305\u62ec\u6210\u5458(\u51fd\u6570)\u6307\u9488)<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_enum;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u679a\u4e3e\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_union;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3aunion<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_class;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u7c7b\u7c7b\u578b\u800c\u4e0d\u662funion<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_function;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u51fd\u6570<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_reference;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u5f15\u7528\u7c7b\u578b(\u5de6\u503c\u5f15\u7528\u6216\u8005\u53f3\u503c\u5f15\u7528)<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_arithmetic;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u6574\u578b\u548c\u6d6e\u70b9\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_fundamental;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u6574\u578b\u3001\u6d6e\u70b9\u3001void\u3001nullptr_t\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_object;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u5bf9\u8c61\u7c7b\u578b(\u4e0d\u662f\u51fd\u6570\u3001\u5f15\u7528\u3001void)<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_scalar;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3aarithmetic\u3001enumeration\u3001pointer\u3001pointer to member\u3001nullptr_t\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_compound;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u975efundamental\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_member_pointer;<\/td><td>\u4fee\u6539\u5224\u65adT\u662f\u5426\u4e3a\u6210\u5458\u51fd\u6570\u6307\u9488\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_polymorphic;<\/td><td>\u5224\u65adT\u662f\u5426\u6709\u865a\u51fd\u6570<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_abstract;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u62bd\u8c61\u7c7b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_signed;<\/td><td>\u5224\u65adT\u662f\u5426\u662f\u6709\u7b26\u53f7\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_unsigned;<\/td><td>\u5224\u65adT\u662f\u5426\u4e3a\u65e0\u7b26\u53f7\u4fee\u6539\u7c7b\u578b<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct is_const;<\/td><td>\u5224\u65adT\u662f\u5426\u6709const\u4fee\u9970\u7b26<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u4e9b\u7c7b\u6a21\u677f\u90fd\u9700\u8981\u901a\u8fc7<code>::value<\/code>\u6765\u8bbf\u95ee\u5224\u65ad\u7ed3\u679c\uff0c\u56e0\u4e3a\u5b83\u4eec\u90fd\u6d3e\u751f\u81ea<code>integral_constant<\/code>\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%88%A4%E6%96%AD%E4%B8%A4%E4%B8%AA%E7%B1%BB%E5%9E%8B%E4%B9%8B%E9%97%B4%E7%9A%84%E5%85%B3%E7%B3%BB\"><\/span>\u5224\u65ad\u4e24\u4e2a\u7c7b\u578b\u4e4b\u95f4\u7684\u5173\u7cfb<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td>traits\u7c7b\u578b<\/td><td>\u8bf4\u660e<\/td><\/tr><tr><td>template&lt;class T, class U&gt;<br>struct is_same;<\/td><td>\u5224\u65ad\u4e24\u4e2a\u7c7b\u578b\u662f\u5426\u76f8\u540c<\/td><\/tr><tr><td>template&lt;class Base, class Derived&gt;<br>struct is_base_of;<\/td><td>\u5224\u65adBase\u7c7b\u578b\u662f\u5426\u4e3aDerived\u7c7b\u578b\u7684\u57fa\u7c7b<\/td><\/tr><tr><td>template&lt;class From, class To&gt;<br>struct is_convertible;<\/td><td>\u5224\u65ad\u524d\u9762\u7684\u6a21\u677f\u53c2\u6570\u7c7b\u578b\u80fd\u5426\u8f6c\u6362\u4e3a\u540e\u9762\u7684\u6a21\u677f\u53c2\u6570\u7c7b\u578b<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E7%B1%BB%E5%9E%8B%E8%BD%AC%E6%8D%A2\"><\/span>\u7c7b\u578b\u8f6c\u6362<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e3b\u8981\u5305\u62ec\u5bf9<code>const<\/code>\u4fee\u9970\u7b26\u3001\u5f15\u7528\u3001\u6570\u7ec4\u548c\u6307\u9488\u7684\u4fee\u6539\u3002<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td>traits\u7c7b\u578b<\/td><td>\u8bf4\u660e<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct remove_const;<\/td><td>\u79fb\u9664const<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct add_const;<\/td><td>\u6dfb\u52a0const<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct remove_reference;<\/td><td>\u79fb\u9664\u5f15\u7528<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct add_lvalue_reference;<\/td><td>\u6dfb\u52a0\u5de6\u503c\u5f15\u7528<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct add_rvalue_reference;<\/td><td>\u6dfb\u52a0\u53f3\u503c\u5f15\u7528<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct remove_extent;<\/td><td>\u79fb\u9664\u6570\u7ec4\u9876\u5c42\u7684\u7ef4\u5ea6<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct remove_all_extents;<\/td><td>\u79fb\u9664\u6570\u7ec4\u6240\u6709\u7684\u7ef4\u5ea6<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct remove_pointer;<\/td><td>\u79fb\u9664\u6307\u9488<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct add_pointer;<\/td><td>\u6dfb\u52a0\u6307\u9488<\/td><\/tr><tr><td>template&lt;class T&gt;<br>struct decay;<\/td><td>\u79fb\u9664cv\u4fee\u9970\u7b26\u6216\u6dfb\u52a0\u6307\u9488\uff0c\u5177\u4f53\u7684\u89c4\u5219\u89c1https:\/\/en.cppreference.com\/w\/cpp\/types\/decay<\/td><\/tr><tr><td>template&lt;class&#8230; T&gt;<br>struct common_type;<\/td><td>\u83b7\u53d6\u516c\u5171\u7c7b\u578b<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">\u7531\u4e8e\u8fd9\u4e9btraits\u662f\u7528\u4e8e\u751f\u6210\u65b0\u7684\u7c7b\u578b\uff0c\u6240\u4ee5\u9700\u8981\u7528<code>::value<\/code>\u6765\u83b7\u53d6\u7ed3\u679c\u7c7b\u578b\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u5e94\u7528\u4f8b\u5b50\uff0c\u6839\u636e\u6a21\u677f\u53c2\u6570\u7c7b\u578b\u521b\u5efa\u5bf9\u8c61\u65f6\u9700\u8981\u79fb\u9664\u5f15\u7528\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>template&lt;typename T&gt;\ntypename std::remove_reference&lt;T&gt;::type* Create()\n{\n  typedef typename std::remove_reference&lt;T&gt;::type U;\n  return new U();\n}<\/code><\/pre>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"conditional\"><\/span>conditional<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<pre class=\"wp-block-code\"><code>template&lt;bool B, class T, class F&gt;\nstruct conditional;<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u5982\u679c<code>B<\/code>\u4e3a<code>true<\/code>\uff0c\u5219<code>conditional::type<\/code>\u4e3aT,\u5426\u5219\u4e3a<code>F<\/code>\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E8%8E%B7%E5%8F%96%E5%8F%AF%E8%B0%83%E7%94%A8%E5%AF%B9%E8%B1%A1%E8%BF%94%E5%9B%9E%E7%B1%BB%E5%9E%8B\"><\/span>\u83b7\u53d6\u53ef\u8c03\u7528\u5bf9\u8c61\u8fd4\u56de\u7c7b\u578b<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td>\u6a21\u677f<\/td><td>\u8bf4\u660e<\/td><\/tr><tr><td>template&lt;class&nbsp;T&gt;<br>typename&nbsp;<a href=\"http:\/\/en.cppreference.com\/w\/cpp\/types\/add_reference\">std::add_rvalue_reference<\/a>&lt;T&gt;::type&nbsp;declval()&nbsp;noexcept;<\/td><td>\u83b7\u53d6\u7c7b\u578bT\u7684\u4e34\u65f6\u503c\uff0c\u65e0\u8bba\u7c7b\u578bT\u6709\u6ca1\u6709\u6784\u9020\u51fd\u6570\uff0c\u5f97\u5230\u7684\u4e34\u65f6\u503c\u53ea\u80fd\u7528\u4e8edecltype\u5224\u65ad\u7c7b\u578b\uff0c\u4e0d\u80fd\u7528\u4e8e\u6c42\u503c<\/td><\/tr><tr><td>template&lt;&nbsp;class&nbsp;F,&nbsp;class&#8230;&nbsp;ArgTypes&nbsp;&gt;<br>class&nbsp;result_of&lt;F(ArgTypes&#8230;)&gt;;<\/td><td>\u83b7\u53d6\u53ef\u8c03\u7528\u5bf9\u8c61\u7684\u8fd4\u56de\u7c7b\u578b<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"enable_if%E4%B8%8ESFINAE\"><\/span>enable_if\u4e0eSFINAE<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>SFINAE<\/strong>\uff1asubstitution is not an error\u3002\u5c31\u662f\u7f16\u8bd1\u5668\u5728\u5339\u914d\u51fd\u6570\u7684\u65f6\u5019\u4f1a\u5c1d\u8bd5\u7528\u6a21\u677f\u751f\u6210\u76f8\u5e94\u7684\u5339\u914d\u66f4\u7cbe\u786e\u7684\u51fd\u6570\uff0c\u5982\u679c\u6a21\u677f\u4e0d\u80fd\u751f\u6210\u8fd9\u6837\u7684\u51fd\u6570\uff0c\u4e5f\u4e0d\u7b97\u9519\uff0c\u7ee7\u7eed\u5339\u914d\u5176\u4ed6\u7684\u3002<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><tbody><tr><td>\u6a21\u677f<\/td><td>\u8bf4\u660e<\/td><\/tr><tr><td>template&lt;&nbsp;bool&nbsp;B,&nbsp;class&nbsp;T&nbsp;=&nbsp;void&nbsp;&gt;<br>struct&nbsp;enable_if;<\/td><td>\u53ea\u6709\u5728B\u4e3atrue\u7684\u65f6\u5019\uff0cenable_if::type\u624d\u6709\u5b9a\u4e49\uff0c\u5e76\u4e14\u4e3aT<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">enable_if\u7684\u5b9a\u4e49\uff0c\u5176\u5b9e\u5c31\u662f\u6a21\u677f\u7279\u5316\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>template&lt;bool B, class T = void&gt;\nstruct enable_if {};\n \ntemplate&lt;class T&gt;\nstruct enable_if&lt;true, T&gt; { typedef T type; };<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">enable_if\u53ef\u4ee5\u7528\u5728\u8fd4\u56de\u503c\u3001\u6a21\u677f\u5b9a\u4e49\u3001\u7c7b\u6a21\u677f\u7684\u7279\u5316\u3001\u5165\u53c2\u7c7b\u578b\u7b49\u5404\u79cd\u5730\u65b9\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%AF%E5%8F%98%E5%8F%82%E6%95%B0%E6%A8%A1%E6%9D%BF\"><\/span>\u53ef\u53d8\u53c2\u6570\u6a21\u677f<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u5728C++11\u4e4b\u524d\u7c7b\u6a21\u677f\u548c\u51fd\u6570\u6a21\u677f\u53ea\u80fd\u542b\u6709\u56fa\u5b9a\u6570\u91cf\u7684\u6a21\u677f\u53c2\u6570\uff0c\u800cC++11\u5141\u8bb8\u6a21\u677f\u5b9a\u4e49\u4e2d\u542b\u67090\u5230\u4efb\u610f\u4e2a\u6a21\u677f\u53c2\u6570\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7701\u7565\u53f7\u7684\u4f5c\u7528\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u58f0\u660e\u4e00\u4e2a\u53c2\u6570\u5305\uff0c\u8fd9\u4e2a\u53c2\u6570\u5305\u4e2d\u53ef\u4ee5\u5305\u542b0\u5230\u4efb\u610f\u4e2a\u6a21\u677f\u53c2\u6570\uff1b<\/li><li>\u5728\u6a21\u677f\u5b9a\u4e49\u91cc\u9762\uff0cpattern&#8230;\u8868\u8fbe\u5f0f\u7b49\u4ef7\u4e8e\uff1a\u5bf9pattern\u91cc\u9762\u7684\u53c2\u6570\u5305\u7684\u6bcf\u4e00\u4e2a\u53c2\u6570\u5e94\u7528pattern\uff0c\u7136\u540e\u7528\u9017\u53f7\u76f8\u8fde\u3002<\/li><\/ul>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%AF%E5%8F%98%E5%8F%82%E6%95%B0%E6%A8%A1%E6%9D%BF%E5%87%BD%E6%95%B0\"><\/span>\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u51fd\u6570<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<h5 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E9%80%9A%E8%BF%87%E9%80%92%E5%BD%92%E5%B1%95%E5%BC%80%E5%8F%82%E6%95%B0%E5%8C%85\"><\/span>\u901a\u8fc7\u9012\u5f52\u5c55\u5f00\u53c2\u6570\u5305<span class=\"ez-toc-section-end\"><\/span><\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">\u9012\u5f52\u4e5f\u662f\u6709\u4e24\u79cd\uff0c\u4e00\u79cd\u662f\u6a21\u677f\u7279\u5316\u7684\u9012\u5f52\uff0c\u4e00\u79cd\u662f\u901a\u8fc7enable_if\u6765\u9012\u5f52\u3002<\/p>\n\n\n\n<h5 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E9%80%9A%E8%BF%87parameter_pack_expansion%E5%B1%95%E5%BC%80%E5%8F%82%E6%95%B0%E5%8C%85\"><\/span>\u901a\u8fc7parameter pack expansion\u5c55\u5f00\u53c2\u6570\u5305<span class=\"ez-toc-section-end\"><\/span><\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">\u8fd9\u79cd\u65b9\u5f0f\u9700\u8981\u7ed3\u5408\u9017\u53f7\u8868\u8fbe\u5f0f\u548c\u521d\u59cb\u5316\u5217\u8868\u3002<\/p>\n\n\n\n<h4 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%AF%E5%8F%98%E5%8F%82%E6%95%B0%E6%A8%A1%E6%9D%BF%E7%B1%BB\"><\/span>\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b<span class=\"ez-toc-section-end\"><\/span><\/h4>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0e\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u51fd\u6570\u76f8\u6bd4\uff0c\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u7c7b\u591a\u4e86\u4e00\u4e2a\u7528\u7ee7\u627f\u7684\u65b9\u5f0f\u6765\u5c55\u5f00\u53c2\u6570\u5305\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u7ec3\u4e60\u9898<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/www.hackerrank.com\/challenges\/cpp-variadics\/problem\">https:\/\/www.hackerrank.com\/challenges\/cpp-variadics\/problem<\/a><\/p>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"%E5%8F%AF%E5%8F%98%E5%8F%82%E6%95%B0%E6%A8%A1%E6%9D%BF%E5%92%8Ctype_traits%E7%9A%84%E7%BB%BC%E5%90%88%E5%BA%94%E7%94%A8\"><\/span>\u53ef\u53d8\u53c2\u6570\u6a21\u677f\u548ctype_traits\u7684\u7efc\u5408\u5e94\u7528<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u68c0\u9a8c\u81ea\u5df1\u662f\u5426\u771f\u7684\u638c\u63e1\u4e86\u6a21\u677f\uff0c\u770b\u81ea\u5df1\u662f\u5426\u80fd\u5b9e\u73b0\u4f5c\u8005\u63d0\u51fa\u7684\u8fd9\u4e9b\u7528\u6a21\u677f\u5b9e\u73b0\u7684\u5de5\u5177(\u5176\u5b9e\u5728C++11\u4e4b\u540e\u7684\u7248\u672c\u91cc\u6709\u8fd9\u4e9b\u4e1c\u897f)\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>optional<\/li><li>\u60f0\u6027\u6c42\u503c\u7c7blazy<\/li><li>dll\u5e2e\u52a9\u7c7b<\/li><li>lambda\u94fe\u5f0f\u8c03\u7528<\/li><li>any<\/li><li>function_traits<\/li><li>variant<\/li><li>ScopeGuard<\/li><li>tuple_helper<\/li><\/ul>\n","protected":false},"excerpt":{"rendered":"<p>\u4f7f\u7528C++11\u6d88\u9664\u91cd\u590d\uff0c\u63d0\u9ad8\u4ee3\u7801\u8d28\u91cf \u901a\u8fc7\u5b9e\u73b0\u51fd\u6570\u548c\u7c7b\u6211\u4eec\u53ef\u4ee5\u91cd\u7528\u4ee3\u7801\uff0c\u800c\u901a\u8fc7\u5199\u6a21\u677f\u5219\u53ef\u4ee5\u5199\u4e00\u6b21\u4ee3\u7801\u751f\u6210\u591a\u4e2a\u5177\u6709\u76f8\u4f3c\u884c\u4e3a\u7684\u51fd\u6570\u548c\u7c7b\uff0c\u8fdb\u4e00\u6b65\u7cbe\u7b80\u4e86\u4ee3\u7801\u3002C++11\u63d0\u4f9b\u4e86\u66f4\u591a\u7684\u5199\u6a21\u677f\u7684\u5de5\u5177\u7c7b\/\u51fd\u6570\uff0c\u65b9\u4fbf\u6211&#46;&#46;&#46;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[8,7,9],"class_list":["post-73","post","type-post","status-publish","format-standard","hentry","category-10","tag-c","tag-c11","tag-9"],"_links":{"self":[{"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/posts\/73","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=73"}],"version-history":[{"count":9,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/posts\/73\/revisions"}],"predecessor-version":[{"id":88,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=\/wp\/v2\/posts\/73\/revisions\/88"}],"wp:attachment":[{"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=73"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=73"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.cauchyschwarz.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=73"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}