Heir Class Constructor Throws CS7036 "No Argument Given" Exception [closed]

Question

I'm trying to create a class that holds the data for an an attack, called Attack. I also have special attacks that have more properties, and so I wanted to create a different class that inherits all of the properties of Attack while adding some more, so I created a class called Special that inherits Attack.

This is what my class structure looks like:

public class Attack { public Attack() { } public class Special : Attack { public Special() { } } }

My compiler is okay with this. However, as soon as I try adding arguments to the constructor of the Attack class, for example...

public class Attack { public Attack(float damage, float staminaCost) { } public class Special : Attack { public Special() { } } }

My compiler throws an error:

Line 13: There is no argument given that corresponds to the required formal parameter 'damage' of 'Attack.Attack(float, float)'

I don't understand why I'm getting this error. I'm not calling Attack(float damage, float staminaCost), so why is it giving me grief over arguments? I tried un-nesting the classes but it doesn't make a difference. I need the constructor for Attack.Special to take in different arguments. Can someone help me achieve this?

user134830 · Accepted Answer · 2020-01-03 01:33:36Z

By default, when new SpecialAttack() is called, before the SpecialAttack() constructor is hit, parent constructors are hit.

The language lets you omit/ignore typing the explicit call to the constructor, but that's only for no-arg () constructors.

Behind the scenes, the structure in the first example looks more like

public class Attack { public Attack() { } public class Special : Attack { public Special() : base() { } } }

If the parent only has one constructor, and that constructor has arguments, you have to tell the compiler how to invoke the parent constructor. Thankfully it's pretty easy regardless.

public class Attack { public Attack(float damage, float staminaCost) { } public class Special : Attack { public Special(): base(0, 0) { } } }

Thanks for the quick answer. I should add for clarification that I do need my constructor for Attack.Special to take in different arguments than the constructor for Attack. Is this solution going to allow me to do this, or will it make the constructor for Attack.Special become the same as that of Attack? — Agent Tatsu
– Agent Tatsu, Commented Jan 3, 2020 at 1:50
Reading your explanation made me realize that a better solution would be to give Attack a parameterless constructor. Not only would it allow me to omit explicitly calling the parent constructor, I also plan to use XML serialization, and classes serialized with XML must have an explicit parameterless constructor. Thanks for the info! — Agent Tatsu
– Agent Tatsu, Commented Jan 3, 2020 at 1:55
As i consider it more, I wonder if I will need to explicitly define a paramterless constructor for Attack.Special as well, since I plan to serialize those objects as well. Would you happen to know this? — Agent Tatsu
– Agent Tatsu, Commented Jan 3, 2020 at 1:58

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