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Synchronous call to an asynchronous method​

// if CallServiceAsync returns Task (void)
var task = Task.Run(() => CallServiceAsync(url, action));
task.Wait();

Difference between const and readonly​

In C#, both the const and readonly keywords are used to declare constants, but they have some differences in terms of their behavior and usage.

The const keyword is used to declare a compile-time constant.

  • Value: The value of a const variable is evaluated at compile-time and cannot be changed during runtime. It must be a constant expression, such as a literal value or a result of an expression composed of other constant values.

  • Modifier: const variables are implicitly static, which means they belong to the type itself rather than any instance of the type. Initialization: const variables must be assigned a value at the time of declaration.

  • Usage: const can be used with primitive types, enums, and user-defined types. They are typically used for values that are not expected to change over time, such as mathematical constants or configuration values.

  • Example:

    public const int MaxValue = 100;

The readonly keyword is used to declare a runtime constant, which means it can be assigned a value either at the time of declaration or within the constructor of the containing type.

  • Value: The value of a readonly variable can be assigned at runtime, but once assigned, it cannot be changed. It can be a result of a calculation or retrieved from a database, for example.

  • Modifier: readonly variables can be either instance-level or static. For instance-level variables, each instance of the type can have a different value, while static readonly variables have a single value shared across all instances.

  • Initialization: readonly variables can be assigned a value at the time of declaration or within the constructor(s) of the containing type. After that, their value cannot be modified.

  • Usage: readonly is often used when a value needs to be calculated or set at runtime but remains constant throughout the lifetime of the object or type.

  • Example:

    public readonly DateTime CreatedAt = DateTime.Now;

To summarize, const is evaluated at compile-time, has a fixed value, and is implicitly static, while readonly allows for runtime initialization and has a value that remains constant after initialization.