Field in Julia

In Julia, a field in a class is a variable that belongs to the class and can hold any value or data structure. Fields are defined using the struct keyword and assigned values using the constructor of the class.

Here is an example of a simple class with three fields:

struct Person
    name::String
    age::Int64
    address::String
end

In this class, name, age, and address are the fields. To create an instance of this class, we can use the constructor like this:

person1 = Person("John", 25, "123 Main St.")

We can access the fields of person1 using dot notation like this:

println(person1.name)      # Output: John
println(person1.age)       # Output: 25
println(person1.address)   # Output: 123 Main St.

We can also change the value of a field using the dot notation:

person1.address = "456 Park Ave."
println(person1.address)   # Output: 456 Park Ave.

Fields can also hold more complex data structures, like arrays or dictionaries:

struct Student
    name::String
    age::Int64
    grades::Dict{String, Int64}
end
student1 = Student("Alice", 18, Dict("Math" => 95, "English" => 85))

println(student1.grades["Math"])     # Output: 95

student1.grades["Science"] = 90

println(student1.grades["Science"])  # Output: 90