What is difference between constant and readonly ?

Here is the difference between constant and readonly in C#:

Constant

• A constant is a variable whose value cannot be changed after it has been assigned.
• The value of a constant must be known at compile-time.
• Constants are declared using the const keyword.
• Constants can be accessed without creating an instance of the class.
• Constants are stored in the assembly's metadata.
• Constants can be of any primitive data type (int, double, char, etc.) or string.

Example:

public const double PI = 3.14159;

Readonly

• A readonly field is a variable whose value can be assigned only once, either at the declaration or in the constructor.
• The value of a readonly field can be calculated at runtime.
• Readonly fields are declared using the `readonl...