C# Collection:
We have learned about an array in the previous section. C# also includes specialized classes that hold many values or objects in a specific series, that are called 'collection'.
There are two types of collections available in C#: non-generic collections and generic collections. We will learn about non-generic collections in this section.
Every collection class implements the IEnumerable interface so values from the collection can be accessed using a foreach loop.
The System.Collections namespace includes following non-generic collections.
| Non-generic Collections
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Usage
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| ArrayList
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ArrayList stores objects of any type like an array. However, there is no need to specify the size of the ArrayList like with an array as it grows automatically.
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| SortedList
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SortedList stores key and value pairs. It automatically arranges elements in ascending order of key by default.
C# includes both, generic and non-generic SortedList collection.
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| Stack
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Stack stores the values in LIFO style (Last In First Out). It provides a Push() method to add a value and Pop() & Peek() methods to retrieve values. C# includes both, generic and non-generic Stack.
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| Queue
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Queue stores the values in FIFO style (First In First Out). It keeps the order in which the values were added. It provides an Enqueue() method to add values and a Dequeue() method to retrieve values from the collection. C# includes generic and non-generic Queue.
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| Hashtable
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Hashtable stores key and value pairs. It retrieves the values by comparing the hash value of the keys.
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| BitArray
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BitArray manages a compact array of bit values, which are represented as Booleans, where true indicates that the bit is on (1) and false indicates the bit is off (0).
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Let's see each type of collection in the next sections.
