What is constants??

Answer 1

Once you have defined a variable constant it means it cannont be modified the correct way to define one is

const int var = 42;

var+=10; //see here i am trying to directly change the value of var doing this will throw an error.

Answer 2

Constants are those which do not change their value.
we can either use the const keyword or #define preprocessor directive to declare constants.
For example:
const int x=8;
x++;
printf("%d",x);
In this case, u will get a compilation error.
Same is the case with #define
Syntax:
#define x 8
Variables can change their value.
For example:
int x=2;
x++;
printf("%d",x);
The output in this case will be 3.
For more details :
https://www.google.com/amp/s/www.geeksforgeeks.org/constants-in-c/amp/
Hope u understand it better now.

Answer 3

Constants are always their initial value.

X=1 as a constant X will always = 1
The value of X can not be manipulated.

As a variable, the value of X can be manipulated.
X=1, Y=2, X=X+Y

X now is X=3