{"id":615,"date":"2022-05-06T09:36:52","date_gmt":"2022-05-06T02:36:52","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=615"},"modified":"2023-04-04T13:50:02","modified_gmt":"2023-04-04T06:50:02","slug":"csharp-generic-classes","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-generic-classes\/","title":{"rendered":"C# Generic Classes"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn how to use C# generics to define reusable and type-neutral classes.<\/p>\n\n\n\n

Introduction to the C# generic classes<\/h2>\n\n\n\n

The following shows the Stack<\/code> class that allows you to push a string onto a stack or pop the top element out of it:<\/p>\n\n\n

namespace<\/span> CSharpTutorial<\/span>;\n\nclass<\/span> Stack<\/span>\n{\n    int<\/span> current = -1<\/span>;\n\n    string<\/span>[] items;\n\n    public<\/span> Stack<\/span>(int<\/span> size<\/span>)<\/span>\n    {\n        items = new<\/span> string<\/span>[size];\n    }\n\n    public<\/span> bool<\/span> Empty => current == -1<\/span>;\n\n    public<\/span> bool<\/span> Full => current == items.Length - 1<\/span>;\n\n    public<\/span> bool<\/span> Push<\/span>(string<\/span> item<\/span>)<\/span>\n    {\n        if<\/span> (!Full)\n        {\n            items[++current] = item;\n            return<\/span> true<\/span>;\n        }\n        return<\/span> false<\/span>;\n    }\n\n    public<\/span> string<\/span>? Pop() => !Empty ? items[current--] : null<\/span>;\n\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
The Stack<\/code> class works fine with strings. But if you want to have a stack of other types like integer<\/a>, float<\/a>, or objects, you need to create a class for each type.<\/p>\n\n\n\n
To make the Stack<\/code> class more generic and reusable, you can use C# generics<\/a> to define a generic class. The following defines a generic Stack<\/code> class that works with any type.<\/p>\n\n\n
namespace<\/span> CSharpTutorial<\/span>;\n\nclass<\/span> Stack<\/span><T<\/span>>\n{\n    int<\/span> current = -1<\/span>;\n\n    T[] items;\n\n    public<\/span> Stack<\/span>(int<\/span> size<\/span>)<\/span>\n    {\n        items = new<\/span> T[size];\n    }\n\n    public<\/span> bool<\/span> Empty => current == -1<\/span>;\n\n    public<\/span> bool<\/span> Full => current == items.Length - 1<\/span>;\n\n    public<\/span> bool<\/span> Push<\/span>(T item<\/span>)<\/span>\n    {\n        if<\/span> (!Full)\n        {\n            items[++current] = item;\n            return<\/span> true<\/span>;\n        }\n        return<\/span> false<\/span>;\n    }\n\n    public<\/span> T? Pop() => !Empty ? items[current--] : default<\/span>(T);\n\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
First, specify the type (T<\/code>) inside angle brackets <><\/code> that follows the class name:<\/p>\n\n\n
class<\/span> Stack<\/span><T<\/span>><\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Second, use the type (T<\/code>) for the items<\/code> member:<\/p>\n\n\n
T[] items;<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Third, use the type (T<\/code>) in the constructor, pop, and push methods.<\/p>\n\n\n\n
The following shows how to use the Stack<T><\/code> class:<\/p>\n\n\n
\nclass<\/span> Program<\/span>\n{\n    public<\/span> static<\/span> void<\/span> Main<\/span>(string<\/span>[] args<\/span>)<\/span>\n    {\n        var<\/span> colors = new<\/span> Stack<string<\/span>>(3<\/span>);\n\n        colors.Push(\"Red\"<\/span>);\n        colors.Push(\"Green\"<\/span>);\n        colors.Push(\"Blue\"<\/span>);\n\n        while<\/span> (true<\/span>)\n        {\n            var<\/span> color = colors.Pop();\n\n            if<\/span> (color == null<\/span>)\n            {\n                break<\/span>;\n            }\n\n            Console.WriteLine(color);\n        }\n\n    }\n\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
First, create a new instance of the Stack<\/code> and specify the string<\/code> as the type:<\/p>\n\n\n
var<\/span> colors = new<\/span> Stack<string<\/span>>(3<\/span>);<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Second, call the Push()<\/code> method three times to push the Red<\/code>, Green<\/code>, and Blue<\/code> strings into the stack:<\/p>\n\n\n
colors.Push(\"Red\"<\/span>);\ncolors.Push(\"Green\"<\/span>);\ncolors.Push(\"Blue\"<\/span>);<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Third, pop the string out of the stack until it is empty by calling the Pop()<\/code> method:<\/p>\n\n\n
while<\/span> (true<\/span>)\n{\n    var<\/span> color = colors.Pop();\n\n    if<\/span> (color == null<\/span>)\n    {\n        break<\/span>;\n    }\n\n    Console.WriteLine(color);\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary<\/h2>\n\n\n\n
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  • Use C# generic class to build reusable and type-neutral classes.<\/li>\n<\/ul>\n
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