enum

C# – Get int value from enum

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The simplest way to get an enum’s int value is by casting it to an int. Here’s an example: This outputs the following: When the enum is generic (of type ‘Enum’) You can’t cast a generic ‘Enum’ to int, otherwise you get a compiler error (CS0030 Cannot convert type ‘System.Enum’ to ‘int’). Use Convert.Int32() instead. … Read more

WinForms – ComboBox with enum description

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By default, when you load enum values into a ComboBox, it’ll show the enum names. If you want to show the enum descriptions (from the [Description] attribute) instead, and still be able to get the selected enum value, you can do the following: I’ll show the code for this below. First, let’s say you have … Read more

C# – Check if a property is an enum with reflection

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When you’re using reflection to look at a type’s properties, you can use PropertyInfo.PropertyType.IsEnum to check if the property is an enum. This is helpful when you want to be able to safely call an Enum API method (such as Enum.Parse()) on the reflected type, thus preventing an exception – ArgumentException: Type provided must be … Read more

C# – Enum generic type constraint

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Here’s how you can use Enum as a generic constraint: Note: Microsoft added this feature in C# 7.3. Whenever you have a generic method, it’s a good idea to use generic type constraints. Without constraints, you would have to implement type checking in the generic method and throw exceptions if an invalid type was used. … Read more

C# – Convert a list of strings into a set of enums

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Let’s say you have a list of HTTP status codes that you read in when the service starts up (perhaps from appsettings.json or from the database). Whenever you send an HTTP request, you want to check if the returned status code is in this list of status code. To make things more efficient, you want … Read more

WinForms – How to programmatically check items in CheckedListBox

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A CheckedListBox allows the user to check one or more checkboxes. Sometimes you’ll want to be able to check the boxes programmatically. For example, you may want to allow the user to check or uncheck all boxes at once. Or perhaps you want to persist the values the user checked and load them later. To … Read more

C# – Get a file’s checksum using any hashing algorithm

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This article shows how to get a file’s checksum using any of these hashing algorithms: MD5, SHA1, SHA256, SHA384, and SHA512. If you are only interested getting a specific type of checksum, take a look at the first section. If you’re interested in a general-purpose checksum method that allows you to generate the checksum using … Read more

C# – Fill a dropdown with enum values

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When you need to show enum values in a dropdown (ComboBox control with DropDownStyle=DropDown), it’s a good idea to automatically populate the list, instead of manually setting all of the values. To fill the dropdown with the enum’s values, set the DataSource to Enum.Values(), like this: Read more about how to show the enum’s Description … Read more

JsonException: The JSON value could not be converted to Enum

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When you’re using System.Text.Json to deserialize JSON that contains the string representation of an enum, you get the following exception: System.Text.Json.JsonException: The JSON value could not be converted to <Enum Type> The following JSON would cause this exception. Conference is an enum, and this is using the string representation “NFC” instead of the numeric value … Read more

Refactoring the Switch Statement code smell

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The Switch Statement code smell refers to using switch statements with a type code to get different behavior or data instead of using subclasses and polymorphism. In general, it looks like this: This switch(typeCode) structure is typically spread throughout many methods. This makes the code difficult to extend, and violates the Open-Closed Principle. This principle … Read more

C# – Using custom attributes

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Attributes are used to store additional info about a class/method/property. The attributes are read at runtime and used to change the program’s behavior. Here are a few examples of commonly used built-in attributes: In general, you should try to use built-in attributes when possible. When it makes sense, you can create your own custom attribute. … Read more

Error: Attribute constructor has an invalid parameter type

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Problem When you try to pass in an attribute constructor parameter to a custom attribute, you get one of the following compiler errors: Error CS0181 Attribute constructor parameter has type ‘Color’ which is not a valid attribute parameter type Error CS0655 ‘Color’ is not a valid named attribute argument because it is not a valid … Read more