{"id":4238,"date":"2022-08-22T01:06:39","date_gmt":"2022-08-21T19:36:39","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-why-do-we-need-a-virtual-destructor-with-dynamic-memory-duplicate\/"},"modified":"2022-08-22T01:06:39","modified_gmt":"2022-08-21T19:36:39","slug":"solved-why-do-we-need-a-virtual-destructor-with-dynamic-memory-duplicate","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-why-do-we-need-a-virtual-destructor-with-dynamic-memory-duplicate\/","title":{"rendered":"[Solved] why do we need a virtual destructor with dynamic memory? [duplicate]"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-20957615\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"20957615\" data-parentid=\"20957473\" data-score=\"2\" data-position-on-page=\"2\" data-highest-scored=\"0\" data-question-has-accepted-highest-score=\"0\" itemprop=\"suggestedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<p>Imagine you have this:<\/p>\n<pre><code>class A { \n  public:\n  int* x;     \n}\nclass B : public A {\n  public:\n  int *y;\n}\n\n\nmain() {\n  A *var = new B;\n  delete var;\n}\n<\/code><\/pre>\n<p>Please assume some constructors destructors.<br \/>\nIn this case when you delete A. If you have virtual destructors then the B destructor will be called first to free y, then A&#8217;s to free x.<\/p>\n<p>If it&#8217;s not virtual it will just call A&#8217;s destructor leaking y.<\/p>\n<p>The issue is that the compiler can&#8217;t know beforehand which destructor it should call. Imagine you have a if above that constructs A or B depending on some input and assings it to var.<br \/>\nBy making it virtual you make the compiler deffer the actual call until runtime. At runtime it will know which is the right destructor based on the vtable.<\/p>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">4<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved why do we need a virtual destructor with dynamic memory? [duplicate] <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] Imagine you have this: class A { public: int* x; } class B : public A { public: int *y; } main() { A *var = new B; delete var; } Please assume some constructors destructors. In this case when you delete A. If you have virtual destructors then the B destructor will be &#8230; <a title=\"[Solved] why do we need a virtual destructor with dynamic memory? [duplicate]\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-why-do-we-need-a-virtual-destructor-with-dynamic-memory-duplicate\/\" aria-label=\"More on [Solved] why do we need a virtual destructor with dynamic memory? [duplicate]\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[324,714],"class_list":["post-4238","post","type-post","status-publish","format-standard","hentry","category-solved","tag-c","tag-virtual-destructor"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v26.5 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>[Solved] why do we need a virtual destructor with dynamic memory? 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