C# const

C# const is a keyword used to declare compile-time constants—values that are fixed at compile time and cannot be changed during program execution. It is applied to fields or local variables to enforce immutability, ensuring that the value remains constant throughout the program's lifecycle. Constants must be initialized at declaration and can only be of primitive types (e.g., int, double, string) or null references.

Also known as: C# constant, C# const keyword, C# compile-time constant, C# immutable field, C# fixed value

Why learn C# const?

Developers should use const to define values that are logically immutable, such as mathematical constants (e.g., PI), configuration settings, or magic numbers, to improve code readability and maintainability by avoiding hard-coded values. It is particularly useful in scenarios where the value is known at compile time and will never change, as it allows the compiler to optimize the code by replacing const references with literal values. However, for values that might change or require runtime initialization, readonly or static fields are preferred alternatives.

Learning Resources

• docs: Microsoft Docs: const (C# Reference)
• tutorial: C# Const vs Readonly - Tutorial
• video: C# Fundamentals for Absolute Beginners - Constants
• tutorial: C# in Depth - Constants and Readonly Fields