Programming C# 3.0, 5th Edition

Collection Interfaces

The .NET Framework provides two sets of standard interfaces for enumerating and comparing collections: the traditional (nontype-safe) and the new generic type-safe collections. This book focuses only on the new type-safe collection interfaces, as these are far preferable.

You can declare an ICollection of any specific type by substituting the actual type (e.g., int or string) for the generic type in the interface declaration (<T>).

Tip

C++ programmers take note: C# Generics are similar in syntax and usage to C++ templates. However, because the generic types are expanded to their specific type at runtime, the JIT compiler is able to share code among different instances, dramatically reducing the code bloat that you may see when using templates in C++.

Table 9-2 lists the key generic collection interfaces.^[13]

Table 9-2. Collection interfaces

Interface	Purpose
ICollection<T>	Base interface for generic collections
IEnumerator<T> IEnumerable<T>	Enumerate through a collection using a foreach statement
ICollection<T>	Implemented by all collections to provide the CopyTo( ) method as well as the Count, IsSynchronized, and SyncRoot properties
IComparer<T> IComparable<T>	Compare two objects held in a collection so that the collection can be sorted
IList<T>	Used by array-indexable collections
IDictionary<K,V>	Used for key-/value-based collections such as Dictionary

The IEnumerable<T> Interface

You can support the foreach statement in ListBoxTest by implementing the IEnumerable<T> interface ...