Const vs. Readonly in C#: When Should I Use Each?

The in -depth comparison of const and readonly in the cONST and Readonly

In C#, programmers can use two ways to define constant:

and

. Although they are all used to declare non -variables, the subtle differences determine their applicable scenarios. const readonly const

The field must be initialized with constant value when declaration. They are static, and they can be accessed by grammar. It is important that "embedded" into the code when compiling, which means that modifying the values ​​in the source code will not affect the reactive assembly reward.

Readonly const ClassName.ConstantName const Different from , the

field can be dynamically assigned before the constructor exits. They are not hidden static, and they can use conventional object grammar to access their values. The important thing is that will not be "frozen" until the value is assigned. Any subsequent changes in the source code will be reflected in the concentration of programs referenced.

Precautions

Understanding these subtle differences can help guide the choice of const and readonly. readonly

If you are convinced that a certain value will never change, please use . This ensures that the value is "embedded" into the code, reducing the risk of errors during runtime.

If you have a value that may change or depend on running conditions, please use

. This allows updates without re -compilation of dependencies. const readonly

Consider the following example:

• const If the assembly B references the assembly A and use the value of the
,
• embedded "embedded" into the IL of the assembly set B without re -compilation. Essence On the contrary, readonly The reference to the memory position in the assembly A will be retained, and the changes to the value of the value will immediately be available to the assembly set B without re -compilation.

Conclusion

<code class="language-csharp">public class ConstantVsReadOnly
{
  public const int I_CONST_VALUE = 2;
  public readonly int I_RO_VALUE;

  public ConstantVsReadOnly()
  {
    I_RO_VALUE = 3;
  }
}</code>

and

provide a complementary mechanism for defining the immutable value in C#. By understanding their subtle differences, developers can make wise decisions to ensure code efficiency and flexibility. ConstantVsReadOnly

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