{"id":317,"date":"2022-01-04T08:19:15","date_gmt":"2022-01-04T01:19:15","guid":{"rendered":"https:\/\/csharptutorial.net\/?page_id=317"},"modified":"2022-06-03T13:41:35","modified_gmt":"2022-06-03T06:41:35","slug":"csharp-constants","status":"publish","type":"page","link":"https:\/\/www.csharptutorial.net\/csharp-tutorial\/csharp-constants\/","title":{"rendered":"C# Constants"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you will learn about the C# constants and how to use them effectively.<\/p>\n\n\n\n

Introduction to the C# constants<\/h2>\n\n\n\n

In C#, a constant holds a value that is known at compile time and does not change during the execution of the program. <\/p>\n\n\n\n

To define a constant, you use the const<\/code> keyword with the following syntax:<\/p>\n\n\n

const<\/span> type ConstantName = value<\/span>;<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
C# only allows you to use built-in types except for the object<\/code> as constants. <\/p>\n\n\n\n
If you define constants inside a method, the constants are only accessible within the method. However, if you define constants in a class<\/a>, you can use the access modifiers such as public and private<\/a> to control the accessibility level of the constants. <\/p>\n\n\n\n
C# constants examples<\/h2>\n\n\n\n
Let’s take some examples of using constants.<\/p>\n\n\n\n
1) Using C# constants in a method<\/h3>\n\n\n\n
The following example defines a Converter class with the KgToPound()<\/code> method that converts weight from kilogram to pound:<\/p>\n\n\n
\/\/ Converter.cs<\/span>\n\nclass<\/span> Converter<\/span>\n{\n    public<\/span> decimal<\/span> KgToPound<\/span>(decimal<\/span> weight<\/span>)<\/span> \n    {\n        const<\/span> decimal<\/span> factor = 2.205<\/span>m;\n\n        return<\/span> weight * factor;\n\n    }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
In this KgToPound() method, we define the factor constant with the value 2.205<\/code>. Because the factor is local to the KgToPound() method, you can only use it inside the method. In other words, you cannot use the factor constant in other methods.<\/p>\n\n\n\n
2) Using C# constants in a class<\/h3>\n\n\n\n
The following example redefines the above Converter class that has the Factor constant defined as a class member:<\/p>\n\n\n
\/\/ Converter.cs<\/span>\n\nclass<\/span> Converter<\/span>\n{\n    public<\/span> const<\/span> decimal<\/span> Factor = 2.205<\/span>m;\n\n    public<\/span> decimal<\/span> KgToPound<\/span>(decimal<\/span> weight<\/span>)<\/span> \n    {\n        return<\/span> weight * Factor;\n    }\n\n    public<\/span> decimal<\/span> PoundToKg<\/span>(decimal<\/span> weight<\/span>)<\/span>\n    {\n        return<\/span> weight \/ Factor;\n    }\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
In this example, since the Factor constant is public, it can be accessed both from methods of the Converter class and from outside of the class.<\/p>\n\n\n\n
The following program uses the Converter class to convert the weight from kg to lbs:<\/p>\n\n\n
\/\/ Program.cs<\/span>\n\ndecimal<\/span> weightInKg, weightInLbs;\n\nvar<\/span> converter = new<\/span> Converter();\n\nConsole.WriteLine($\"Convert weight from kg to lbs (factor = {Converter.Factor}<\/span>)\"<\/span>);\n\nwhile<\/span>(true<\/span>)\n{\n    \/\/ Prompt to enter a weight in Kg:<\/span>\n    Console.Write(\"Enter a weight in Kg (0 to exit):\"<\/span>);\n    weightInKg = Convert.ToDecimal(Console.ReadLine());\n    \n    if<\/span>(weightInKg == 0<\/span>)\n    {\n        break<\/span>;\n    }\n    \n    \/\/ convert weight from kg to lbs<\/span>\n    weightInLbs = converter.KgToPound(weightInKg);\n    Console.WriteLine($\"{weightInKg}<\/span>kg = {weightInLbs}<\/span>lbs\"<\/span>);\n}<\/code><\/span>Code language:<\/span> C#<\/span> (<\/span>cs<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
Convert weight from kg to lbs (factor = 2.205)\nEnter a weight in Kg (0 to exit):1\n1kg = 2.205lbs\nEnter a weight in Kg (0 to exit):2\n2kg = 4.410lbs\nEnter a weight in Kg (0 to exit):2.5\n2.5kg = 5.5125lbs\nEnter a weight in Kg (0 to exit):0<\/code><\/span>Code language:<\/span> plaintext<\/span> (<\/span>plaintext<\/span>)<\/span><\/small><\/pre>\n\n\n
Summary<\/h2>\n\n\n\n
  • C# constants are identifiers that hold values that are known at compile-time and do not change during the execution of the program.<\/li><\/ul>\n
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