{"id":25552,"date":"2024-03-16T05:11:36","date_gmt":"2024-03-16T05:11:36","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/how-to-use-the-c-type-conversion-operator-dynamic_cast\/"},"modified":"2024-03-22T06:27:01","modified_gmt":"2024-03-22T06:27:01","slug":"how-to-use-the-c-type-conversion-operator-dynamic_cast","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/how-to-use-the-c-type-conversion-operator-dynamic_cast\/","title":{"rendered":"How to use the C++ type conversion operator dynamic_cast?"},"content":{"rendered":"<p>In C++, `dynamic_cast` is a type-safe casting operator used to safely convert a base class pointer or reference to a derived class pointer or reference. It can check if the conversion is valid at runtime and return the correct pointer or reference.<\/p>\n<p>The syntax of dynamic_cast is as follows:<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-built_in\">dynamic_cast<\/span>&lt;new_type&gt;(expression)\r\n<\/code><\/pre>\n<p>In this case, new_type is the target type to convert to, and expression is the pointer or reference to be converted.<\/p>\n<p>When using dynamic_cast, the following conditions must be met:<\/p>\n<ol>\n<li>The conversion type must be a pointer or reference type, not a basic type.<\/li>\n<li>The converted type must be a class type, not a void pointer.<\/li>\n<li>There must be an inheritance relationship between the source type and the target type.<\/li>\n<\/ol>\n<p>When using dynamic_cast, the following checks will be performed:<\/p>\n<ol>\n<li>If the conversion is successful, return the converted pointer or reference.<\/li>\n<li>If the conversion fails and the target type is a pointer type, return a null pointer.<\/li>\n<li>If the conversion fails and the target type is a reference type, it will throw a std::bad_cast exception.<\/li>\n<\/ol>\n<p>Here is an example using dynamic_cast:<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-meta\">#<span class=\"hljs-keyword\">include<\/span> <span class=\"hljs-string\">&lt;iostream&gt;<\/span><\/span>\r\n\r\n<span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">Base<\/span> {\r\n<span class=\"hljs-keyword\">public<\/span>:\r\n    <span class=\"hljs-function\"><span class=\"hljs-keyword\">virtual<\/span> <span class=\"hljs-type\">void<\/span> <span class=\"hljs-title\">print<\/span><span class=\"hljs-params\">()<\/span> <\/span>{\r\n        std::cout &lt;&lt; <span class=\"hljs-string\">\"Base\"<\/span> &lt;&lt; std::endl;\r\n    }\r\n};\r\n\r\n<span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">Derived<\/span> : <span class=\"hljs-keyword\">public<\/span> Base {\r\n<span class=\"hljs-keyword\">public<\/span>:\r\n    <span class=\"hljs-function\"><span class=\"hljs-type\">void<\/span> <span class=\"hljs-title\">print<\/span><span class=\"hljs-params\">()<\/span> <span class=\"hljs-keyword\">override<\/span> <\/span>{\r\n        std::cout &lt;&lt; <span class=\"hljs-string\">\"Derived\"<\/span> &lt;&lt; std::endl;\r\n    }\r\n};\r\n\r\n<span class=\"hljs-function\"><span class=\"hljs-type\">int<\/span> <span class=\"hljs-title\">main<\/span><span class=\"hljs-params\">()<\/span> <\/span>{\r\n    Base* basePtr = <span class=\"hljs-keyword\">new<\/span> Derived;\r\n    \r\n    Derived* derivedPtr = <span class=\"hljs-built_in\">dynamic_cast<\/span>&lt;Derived*&gt;(basePtr);\r\n    <span class=\"hljs-keyword\">if<\/span> (derivedPtr) {\r\n        derivedPtr-&gt;<span class=\"hljs-built_in\">print<\/span>(); <span class=\"hljs-comment\">\/\/ \u8f93\u51fa \"Derived\"<\/span>\r\n    } <span class=\"hljs-keyword\">else<\/span> {\r\n        std::cout &lt;&lt; <span class=\"hljs-string\">\"Failed to cast\"<\/span> &lt;&lt; std::endl;\r\n    }\r\n    \r\n    <span class=\"hljs-keyword\">delete<\/span> basePtr;\r\n    <span class=\"hljs-keyword\">return<\/span> <span class=\"hljs-number\">0<\/span>;\r\n}\r\n<\/code><\/pre>\n<p>In the given example, the Base class is a base class, and the Derived class is a derived class that inherits from the Base class. First, an object of the Derived class is created and assigned to a Base class pointer called basePtr. Then, dynamic_cast is used to convert basePtr into a pointer of type Derived class called derivedPtr. Since Derived class is a derived class of Base class, the conversion is valid and derivedPtr will point to an object of the Derived class. Finally, the print() function of derivedPtr is called, which outputs &#8220;Derived&#8221;.<\/p>\n<p>It is important to note that dynamic_cast can only be used for polymorphic types (i.e. classes with virtual functions) because it requires type checking at runtime. Using dynamic_cast on non-polymorphic types will result in a compilation error.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In C++, `dynamic_cast` is a type-safe casting operator used to safely convert a base class pointer or reference to a derived class pointer or reference. It can check if the conversion is valid at runtime and return the correct pointer or reference. The syntax of dynamic_cast is as follows: dynamic_cast&lt;new_type&gt;(expression) In this case, new_type is [&hellip;]<\/p>\n","protected":false},"author":10,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-25552","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.5 (Yoast SEO v21.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>How to use the C++ type conversion operator dynamic_cast? - Blog - Silicon Cloud<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.silicloud.com\/blog\/how-to-use-the-c-type-conversion-operator-dynamic_cast\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How to use the C++ type conversion operator dynamic_cast?\" \/>\n<meta property=\"og:description\" content=\"In C++, `dynamic_cast` is a type-safe casting operator used to safely convert a base class pointer or reference to a derived class pointer or reference. 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