Is it mandatory to have a constructor in a class for it to work correctly?

Having a constructor in a class is not always necessary for it to function correctly. If no constructor is declared in the class, the compiler automatically creates a default constructor without parameters.

However, if parameterized initialization or special logic during object creation is needed, then the constructor should be explicitly declared.

Example in Swift:

class Person {
    var name: String
    
    // Constructor is required because there is a mandatory property without a default value
    init(name: String) {
        self.name = name
    }
}

If all properties have default values, then the constructor can be omitted, and the class will work correctly.