Constants
When you do not want others (or yourself) to change existing variable values, use the const keyword (this will declare the variable as “constant”, which means 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 the variable as constant when you have values that are unlikely to change:
Example
const int minutesPerHour = 60;
Notes On Constants
When you declare a constant variable, it must be assigned with a value:
Example
Like this:
const int minutesPerHour = 60;
This however, will not work:
const int minutesPerHour;
minutesPerHour = 60; // error