In Julia, constants are defined with the const keyword. Constants are used for values that should not be changed throughout the program. Here is an example:
const pi = 3.14159
In this example, pi is declared as a constant with the value 3.14159. Since pi is declared as a constant, its value cannot be changed throughout the program.
Here are a few more examples:
const message = "Hello, world!" # string constant
const my_age = 30 # integer constant
const weight = 68.5 # float constant
In these examples, message is a constant string with the value "Hello, world!", my_age is a constant integer with the value 30, and weight is a constant float with the value 68.5.
Once a constant has been defined, its value cannot be changed. Attempting to do so will result in a compile-time error.