How to: Explicitly Implement Interface Members (C# Programming Guide)
Visual Studio 2012
This example declares an interface, IDimensions, and a class, Box, which explicitly implements the interface members getLength and getWidth. The members are accessed through the interface instance dimensions.
interface IDimensions { float getLength(); float getWidth(); } class Box : IDimensions { float lengthInches; float widthInches; Box(float length, float width) { lengthInches = length; widthInches = width; } // Explicit interface member implementation: float IDimensions.getLength() { return lengthInches; } // Explicit interface member implementation: float IDimensions.getWidth() { return widthInches; } static void Main() { // Declare a class instance box1: Box box1 = new Box(30.0f, 20.0f); // Declare an interface instance dimensions: IDimensions dimensions = (IDimensions)box1; // The following commented lines would produce compilation // errors because they try to access an explicitly implemented // interface member from a class instance: //System.Console.WriteLine("Length: {0}", box1.getLength()); //System.Console.WriteLine("Width: {0}", box1.getWidth()); // Print out the dimensions of the box by calling the methods // from an instance of the interface: System.Console.WriteLine("Length: {0}", dimensions.getLength()); System.Console.WriteLine("Width: {0}", dimensions.getWidth()); } } /* Output: Length: 30 Width: 20 */
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Notice that the following lines, in the Main method, are commented out because they would produce compilation errors. An interface member that is explicitly implemented cannot be accessed from a class instance:
//System.Console.WriteLine("Length: {0}", box1.getLength()); //System.Console.WriteLine("Width: {0}", box1.getWidth());
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Notice also that the following lines, in the Main method, successfully print out the dimensions of the box because the methods are being called from an instance of the interface:
System.Console.WriteLine("Length: {0}", dimensions.getLength()); System.Console.WriteLine("Width: {0}", dimensions.getWidth());