C# FAQ: How can type name clashes be resolved

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How can type name clashes be resolved?

The C# using keyword can be used to supply hints to the C# compiler regarding the fully qualified names of types residing in a specified source (.cs) file. The using keyword can include an alias which can be used to prevent or resolve name clashes.

Assume the following namespace definitions:

namespace Namespace1
{
   public class SampleClass {}  // same classname as below
}
 
namespace Namespace2
{
   public class SampleClass {}  // same classname as above
}

Next, the application tries to create an instance of the Namespace2.SampleClass from the following application:

using Namespace1;
using Namespace2;
 
public class SampleApplication
{
  public static void Main()
  {
    SampleClass sc = new SampleClass ();    
    // Compiler error:  type name clash: 
    // Namespace1.SampleClass or Namespace2.SampleClass ?
  }
}

The resulting type name clash can be resolved by creating an alias as follows:

using Namespace1;
using SampleClass2 = Namespace2.SampleClass;
 
public class SampleApplication
{
  public static void Main()
  {
    SampleClass2 sc = new SampleClass2();    
    // Creates a new Namespace2.SampleClass. Same as: 
    // Namespace2.SampleClass sc = new Namespace2.SampleClass();
  }
}

The using keyword can also be used to resolve type name conflicts for types with "System" in their fully qualified names.