// Creates an empty CodeTypeDeclarationCollection.
CodeTypeDeclarationCollection collection = new CodeTypeDeclarationCollection();

// Adds a CodeTypeDeclaration to the collection.
collection.Add( new CodeTypeDeclaration("TestType") );

// Adds an array of CodeTypeDeclaration objects to the collection.
CodeTypeDeclaration[] declarations = { new CodeTypeDeclaration("TestType1"), new CodeTypeDeclaration("TestType2") };
collection.AddRange( declarations );

// Adds a collection of CodeTypeDeclaration objects to the 
// collection.
CodeTypeDeclarationCollection declarationsCollection = new CodeTypeDeclarationCollection();
declarationsCollection.Add( new CodeTypeDeclaration("TestType1") );
declarationsCollection.Add( new CodeTypeDeclaration("TestType2") );
collection.AddRange( declarationsCollection );

// Tests for the presence of a CodeTypeDeclaration in the 
// collection, and retrieves its index if it is found.
CodeTypeDeclaration testDeclaration = new CodeTypeDeclaration("TestType");
int itemIndex = -1;
if( collection.Contains( testDeclaration ) )
    itemIndex = collection.IndexOf( testDeclaration );

// Copies the contents of the collection, beginning at index 0,
// to the specified CodeTypeDeclaration array.
// 'declarations' is a CodeTypeDeclaration array.
collection.CopyTo( declarations, 0 );

// Retrieves the count of the items in the collection.
int collectionCount = collection.Count;

// Inserts a CodeTypeDeclaration at index 0 of the collection.
collection.Insert( 0, new CodeTypeDeclaration("TestType") );

// Removes the specified CodeTypeDeclaration from the collection.
CodeTypeDeclaration declaration = new CodeTypeDeclaration("TestType");
collection.Remove( declaration );

// Removes the CodeTypeDeclaration at index 0.
collection.RemoveAt(0);