{"id":403,"date":"2022-01-06T11:47:51","date_gmt":"2022-01-06T04:47:51","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=403"},"modified":"2022-06-03T15:02:39","modified_gmt":"2022-06-03T08:02:39","slug":"csharp-sealed","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-sealed\/","title":{"rendered":"C# sealed"},"content":{"rendered":"\n<p><strong>Summary<\/strong>: in this tutorial, you&#8217;ll learn how to use the C# sealed modifier to prevent a class from inheriting by other classes or a class member from overriding by a member in the subclass.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Introduction to the C# sealed modifier<\/h2>\n\n\n\n<p>When <a href=\"https:\/\/csharptutorial.net\/csharp-tutorial\/csharp-class\/\">creating a class<\/a>, you should consider the following points:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>The benefits that other classes may gain by inheriting from your class.<\/li><li>The side effects if other classes extend your class in such as way that it would no longer work correctly or as expected. <\/li><\/ul>\n\n\n\n<p>If the second point is obvious, you can prevent it by using the C# <code>sealed<\/code> modifier.<\/p>\n\n\n\n<p>When you apply the <code>sealed<\/code> modifier to a class, you prevent other classes from <a href=\"https:\/\/csharptutorial.net\/csharp-tutorial\/csharp-inheritance\/\">inheriting<\/a> it:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-1\" data-shcb-language-name=\"C#\" data-shcb-language-slug=\"cs\"><span><code class=\"hljs language-cs\"><span class=\"hljs-keyword\">sealed<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">MyClass<\/span>\n{\n}<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-1\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">C#<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">cs<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this example, we use the <code>sealed<\/code> modifier for the  <code>MyClass<\/code> so that other classes cannot <a href=\"https:\/\/csharptutorial.net\/csharp-tutorial\/csharp-inheritance\/\">inherit<\/a> from it. If you attempt to subclass the <code>MyClass<\/code>, you&#8217;ll get an error. For example:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-2\" data-shcb-language-name=\"C#\" data-shcb-language-slug=\"cs\"><span><code class=\"hljs language-cs\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">MySubclass<\/span>: <span class=\"hljs-title\">MyClass<\/span>\n{\n\n}<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-2\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">C#<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">cs<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Error:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-3\" data-shcb-language-name=\"C#\" data-shcb-language-slug=\"cs\"><span><code class=\"hljs language-cs\"><span class=\"hljs-string\">'MySubclass'<\/span>: cannot derive <span class=\"hljs-keyword\">from<\/span> <span class=\"hljs-keyword\">sealed<\/span> type <span class=\"hljs-string\">'MyClass'<\/span><\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-3\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">C#<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">cs<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>Also, you can apply the <code>sealed<\/code> modifier to a <a href=\"https:\/\/csharptutorial.net\/csharp-tutorial\/csharp-property\/\">property<\/a> or method that overrides a <a href=\"https:\/\/csharptutorial.net\/csharp-tutorial\/csharp-virtual\/\">virtual<\/a> property or method. The sealed properties and methods seal their implementations to prevent overriding. For example:<\/p>\n\n\n<pre class=\"wp-block-code\" aria-describedby=\"shcb-language-4\" data-shcb-language-name=\"C#\" data-shcb-language-slug=\"cs\"><span><code class=\"hljs language-cs\"><span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">MyClass<\/span>\n{\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">virtual<\/span> <span class=\"hljs-keyword\">string<\/span> Name { <span class=\"hljs-keyword\">get<\/span>; <span class=\"hljs-keyword\">set<\/span>; }\n    <span class=\"hljs-function\"><span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">virtual<\/span> <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title\">MyMethod<\/span>(<span class=\"hljs-params\"><\/span>)<\/span> { }\n\n}\n\n<span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title\">Subclass<\/span> : <span class=\"hljs-title\">MyClass<\/span>\n{\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">sealed<\/span> <span class=\"hljs-keyword\">override<\/span> <span class=\"hljs-keyword\">string<\/span> Name { <span class=\"hljs-keyword\">get<\/span>; <span class=\"hljs-keyword\">set<\/span>; }\n\n    <span class=\"hljs-function\"><span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">sealed<\/span> <span class=\"hljs-keyword\">override<\/span> <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title\">MyMethod<\/span>(<span class=\"hljs-params\"><\/span>)<\/span> { }\n}<\/code><\/span><small class=\"shcb-language\" id=\"shcb-language-4\"><span class=\"shcb-language__label\">Code language:<\/span> <span class=\"shcb-language__name\">C#<\/span> <span class=\"shcb-language__paren\">(<\/span><span class=\"shcb-language__slug\">cs<\/span><span class=\"shcb-language__paren\">)<\/span><\/small><\/pre>\n\n\n<p>In this example, the subclasses of the <code>MySubclass<\/code> cannot override the <code>Name<\/code> property and <code>MyMethod<\/code> method.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Summary<\/h2>\n\n\n\n<ul class=\"wp-block-list\"><li>Use the <code>sealed<\/code> modifier for a class to prevent it from being subclassed by other classes.<\/li><li>Use the <code>sealed<\/code> modifier for a property or a method to prevent it from being overridden by the members in the subclasses.<\/li><\/ul>\n<div class=\"helpful-block-content\" data-title=\"\">\n\t<header>\n\t\t<div class=\"wth-question\">Was this tutorial helpful ?<\/div>\n\t\t<div class=\"wth-thumbs\">\n\t\t\t<button\n\t\t\t\tdata-post=\"403\"\n\t\t\t\tdata-post-url=\"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-sealed\/\"\n\t\t\t\tdata-post-title=\"C# sealed\"\n\t\t\t\tdata-response=\"1\"\n\t\t\t\tclass=\"wth-btn-rounded wth-yes-btn\"\n\t\t\t>\n\t\t\t\t<svg\n\t\t\t\t\txmlns=\"http:\/\/www.w3.org\/2000\/svg\"\n\t\t\t\t\tviewBox=\"0 0 24 24\"\n\t\t\t\t\tfill=\"none\"\n\t\t\t\t\tstroke=\"currentColor\"\n\t\t\t\t\tstroke-width=\"2\"\n\t\t\t\t\tstroke-linecap=\"round\"\n\t\t\t\t\tstroke-linejoin=\"round\"\n\t\t\t\t\tclass=\"feather feather-thumbs-up block w-full h-full\"\n\t\t\t\t>\n\t\t\t\t\t<path\n\t\t\t\t\t\td=\"M14 9V5a3 3 0 0 0-3-3l-4 9v11h11.28a2 2 0 0 0 2-1.7l1.38-9a2 2 0 0 0-2-2.3zM7 22H4a2 2 0 0 1-2-2v-7a2 2 0 0 1 2-2h3\"\n\t\t\t\t\t><\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t<span class=\"sr-only\"> Yes <\/span>\n\t\t\t<\/button>\n\n\t\t\t<button\n\t\t\t\tdata-response=\"0\"\n\t\t\t\tdata-post=\"403\"\n\t\t\t\tdata-post-url=\"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-sealed\/\"\n\t\t\t\tdata-post-title=\"C# sealed\"\n\t\t\t\tclass=\"wth-btn-rounded wth-no-btn\"\n\t\t\t>\n\t\t\t\t<svg\n\t\t\t\t\txmlns=\"http:\/\/www.w3.org\/2000\/svg\"\n\t\t\t\t\tviewBox=\"0 0 24 24\"\n\t\t\t\t\tfill=\"none\"\n\t\t\t\t\tstroke=\"currentColor\"\n\t\t\t\t\tstroke-width=\"2\"\n\t\t\t\t\tstroke-linecap=\"round\"\n\t\t\t\t\tstroke-linejoin=\"round\"\n\t\t\t\t>\n\t\t\t\t\t<path\n\t\t\t\t\t\td=\"M10 15v4a3 3 0 0 0 3 3l4-9V2H5.72a2 2 0 0 0-2 1.7l-1.38 9a2 2 0 0 0 2 2.3zm7-13h2.67A2.31 2.31 0 0 1 22 4v7a2.31 2.31 0 0 1-2.33 2H17\"\n\t\t\t\t\t><\/path>\n\t\t\t\t<\/svg>\n\t\t\t\t<span class=\"sr-only\"> No <\/span>\n\t\t\t<\/button>\n\t\t<\/div>\n\t<\/header>\n\n\t<div class=\"wth-form hidden\">\n\t\t<div class=\"wth-form-wrapper\">\n\t\t\t<div class=\"wth-title\"><\/div>\n\t\t\t\n\t\t\t<textarea class=\"wth-message\"><\/textarea>\n\n\t\t\t<button class=\"btn btn-primary wth-btn-submit\">Send<\/button>\n\t\t\t<button class=\"btn wth-btn-cancel\">Cancel<\/button>\n\t\t\n\t\t<\/div>\n\t<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>In this tutorial, you&#8217;ll learn how to use the C# sealed modifier to prevent a class from inheriting by other classes or a member of a class from overriding by a member in the subclass.<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":7,"menu_order":45,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-403","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.csharptutorial.net\/wp-json\/wp\/v2\/pages\/403","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.csharptutorial.net\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.csharptutorial.net\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.csharptutorial.net\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.csharptutorial.net\/wp-json\/wp\/v2\/comments?post=403"}],"version-history":[{"count":5,"href":"https:\/\/www.csharptutorial.net\/wp-json\/wp\/v2\/pages\/403\/revisions"}],"predecessor-version":[{"id":721,"href":"https:\/\/www.csharptutorial.net\/wp-json\/wp\/v2\/pages\/403\/revisions\/721"}],"up":[{"embeddable":true,"href":"https:\/\/www.csharptutorial.net\/wp-json\/wp\/v2\/pages\/7"}],"wp:attachment":[{"href":"https:\/\/www.csharptutorial.net\/wp-json\/wp\/v2\/media?parent=403"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}