[c#] Inheritance with base class constructor with parameters

Simple code:

class foo
{
    private int a;
    private int b;

    public foo(int x, int y)
    {
        a = x;
        b = y;
    }
}

class bar : foo
{
    private int c;
    public bar(int a, int b) => c = a * b;
}

Visual Studio complains about the bar constructor:

Error CS7036 There is no argument given that corresponds to the required formal parameter x of foo.foo(int, int).

What?

This question is related to c# inheritance constructor

The answer is


I could be wrong, but I believe since you are inheriting from foo, you have to call a base constructor. Since you explicitly defined the foo constructor to require (int, int) now you need to pass that up the chain.

public bar(int a, int b) : base(a, b)
{
     c = a * b;
}

This will initialize foo's variables first and then you can use them in bar. Also, to avoid confusion I would recommend not naming parameters the exact same as the instance variables. Try p_a or something instead, so you won't accidentally be handling the wrong variable.


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