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Compiler Error CS1018

Keyword 'this' or 'base' expected

The compiler encountered an incomplete constructor declaration.

The following example generates CS1018, and suggests several ways to resolve the error:

// CS1018.cs
public class C
{
}

public class a : C
{
    public a(int i)
    {
    }

    public a () :   // CS1018
    // possible resolutions:
    // public a () resolves by removing the colon
    // public a () : base() calls C's default constructor
    // public a () : this(1) calls the assignment constructor of class a
    {
    }

    public static int Main()
    {
        return 1;
    }
}
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