What is the difference between const and static readonly?

The difference is that the value of a readonly field is set at run time, so it can have a different value for different executions of the program. However, the value of a const field is set to a compile time constant.

 

 

Readonly instance fields

• Must have set value, by the time constructor exits
• Are evaluated when instance is created

Static readonly fields

• Are evaluated when code execution hits class reference (when new instance is created or a static method is executed)
• Must have an evaluated value by the time the static constructor is done
• It's not recommended to put ThreadStaticAttribute on these (static constructors will be executed in one thread only and will set the value for its thread; all other threads will have this value uninitialized)

Constants

• Constants are static by default
• They must have a value at compilation-time
• Could be declared within functions
• Are copied into every assembly that uses them
• Can be used in attributes

 

 

Check this video out for more understanding :

 

C# Concepts,Keywords
- YouTube