C# Programming/Keywords/readonly

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The readonly keyword is closely related to the const keyword at a glance, with the exception of allowing a variable with this modifier to be initialized in a constructor, along with being associated with a class instance (object) rather than the class itself.

The primary use for this keyword is to allow the variable to take on different values depending on which constructor was called, in case the class has many, while still ensuring the developer that it can never intentionally or unintentionally be changed in the code once the object has been created.

This is a sample usage, assumed to be in a class called SampleClass:

readonly string s;

    s = "Hello!";

C# Keywords
abstract as base bool break
byte case catch char checked
class const continue decimal default
delegate do double else enum
event explicit extern false finally
fixed float for foreach
goto if implicit in int
interface internal is lock long
namespace new null object operator
out override params private protected
public readonly ref return sbyte
sealed short sizeof stackalloc
static string struct switch this
throw true try typeof uint
ulong unchecked unsafe ushort using
var virtual void volatile while
Special C# Identifiers
add alias get global partial
remove set value where yield