Use of const keyword in C#

Okay.

1 Kilometer=1000 meters, can you change it? No, this is universal contant.

Pie= 3.14, can you change it? Yes, you can take n numbers after decimal (3.142567). This is partial constant.

So, whenever you are dealing with universal constant that will never ever change, you use const.

when you need some values to change but only at runtime you use readonly, you set the value at configuration and read it inside the class constructor.

Now, Why we can only use const keyword with primitive type

Ans:- Primitive types are value types, means they can not be changed by chaging the value to their location.

ex:-

int x=10;
int y=x; // y=10
x++; // x=11
Console.Write(y); // still 10

so, compiler assign the value at the compile time, you can test it using ILDASM tool, (go to cmd-->Ildasam pathof your exe/class).

That is the reason, Const are called compile time constant.

This is not possible with reference type like userdefined datatype like class or even struct.

2 Replies

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Amit Mohanty4y ago
Accepted answer
Hey, check the below link. this may clear you doubt.

https://www.onlinebuff.com/article_understand-constants-in-c-with-an-example_51.html
+2
Sachin Singh4y ago
Okay.
1 Kilometer=1000 meters, can you change it? No, this is universal contant.
Pie= 3.14, can you change it? Yes, you can take n numbers after decimal (3.142567). This is partial constant.

So, whenever you are dealing with universal constant that will never ever change, you use const.
when you need some values to change but only at runtime you use readonly, you set the value at configuration and read it inside the class constructor.

Now, Why we can only use const keyword with primitive type
Ans:- Primitive types are value types, means they can not be changed by chaging the value to their location.
ex:-
int x=10;
      int y=x; // y=10
      x++; // x=11
      Console.Write(y); // still 10
so, compiler assign the value at the compile time, you can test it using ILDASM tool, (go to cmd-->Ildasam pathof your exe/class).
That is the reason, Const are called compile time constant.
This is not possible with reference type like userdefined datatype like class or even struct.
+4