Compiler Error CS1019

Overloadable unary operator expected

Something that looks like an overloaded unary operator has been declared, but the operator is missing or is in the wrong ___location in the signature.

A unary operator is an operator that operates on a single operand. For example, ++ is a unary operator. You can overload some unary operators by using the operator keyword and specifying a single parameter of the type that the operator operates on. For example, if you want to overload the operator ++ for a user-defined class Temperature so that you can write Temperature++, you can define it in this way:

public static  Temperature operator ++ (Temperature temp)
{
    temp.Degrees++;
    return temp;
}

When you receive this error, you have declared something that looks like an overloaded unary operator, except that the operator itself is missing or is in the wrong ___location in the signature. If you remove the ++ from the signature in the previous example, you will generate CS1019.

The following code generates CS1019:

// CS1019.cs
public class ii
{
   int i
   {
      get
      {
         return 0;
      }
   }
}

public class a
{
    public int i;
// Generates CS1019: "ii" is not a unary operator.
   public static a operator ii(a aa)   
                                       
   // Use the following line instead:
   //public static a operator ++(a aa)
   {
      aa.i++;
      return aa; 
   }

   public static void Main()
   {
   }
}

See Also

Reference

Operators (C# Programming Guide)

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