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C# C# Objects Inheritance Custom Exceptions

michaelcodes
michaelcodes
5,604 Points
Posted by michaelcodes
michaelcodes
5,604 Points

Confused about the :base constructor and how it works?

I am confused about how the base constructor works. I understand that it takes the parent classes constructor parameter but in what way? In the code below:

      public MapLocation(int x, int y, Map map) : base(x,y){

        if(!map.OnMap(this)) {
          throw new OutOfBoundsException(x + "," + y + " is out of bounds!");

        }

Why did we initialize new variables for MapLocation (x and y), but then we also have :base(x,y) if they are not used? Also do these variables need to be named the same as they are in the parent constructor or does it not matter?

This is very confusing to me if anyone can explain how this is working it would be greatly appreciated!

2 Answers

Steven Parker
Steven Parker
231,261 Points
Steven Parker
Steven Parker
231,261 Points

The variables are passed to the parent constructor, because they are used by the parent constructor. They are also used in this constructor to build the exception error message.

The variable names do not have to be the same as in the parent constructor, but doing so might help to make their purpose clear.

michaelcodes
michaelcodes
5,604 Points
michaelcodes
michaelcodes
5,604 Points

I understand a bit better. So when the object is created using:

MapLocation maplocation = new MapLocation(20,20,map);

You are sending the parameters for the MapLocation x and y. Where is the base getting its x and y value? Are they also passed along and are the same as the param values above?

Thanks for the help!

Steven Parker
Steven Parker
231,261 Points
Steven Parker
Steven Parker
231,261 Points

The base gets the x and y values from the ": base(x,y)" call of the MapLocation constructor. They are passed along unchanged, so in this example they would both be 20.

michaelcodes
michaelcodes
5,604 Points
michaelcodes
michaelcodes
5,604 Points

Ahh, thank you for all your help I think I have a better understanding now. I am sure it will become more clear as I continue in my learnings.

Take care and happy coding!

Evan Welch
Evan Welch
1,815 Points
Evan Welch
Evan Welch
1,815 Points

So base just refers to the parent class?