How to: Explicitly Implement Interface Members (C# Programming Guide)
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.
Example
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
*/
Robust Programming
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());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());
See Also
Tasks
How to: Explicitly Implement Members of Two Interfaces (C# Programming Guide)