Constants
Now that you have seen different types of variables in C, you should also know that sometimes you need variables that should not change.
This can be done with the const keyword, which makes a variable unchangeable and read-only:
Example
const int myNum = 15; // myNum will always be 15
myNum = 10; // error:
assignment of read-only variable 'myNum'
You should always declare a variable as const when you have values that are unlikely to change:
Example
const int minutesPerHour = 60;
const int
monthsInYear = 12;
Notes On Constants
When you declare a constant variable, it must be assigned with a value:
Example
const int minutesPerHour = 60;
Good Practice
Another thing about constant variables, is that it is considered good practice to declare them with uppercase.
It is not required, but useful for code readability and common for C programmers:
Example
const int BIRTHYEAR = 1980;
