70-536 exam: StringCollection class
12 March 2010
Following on my blog post about Hashtables, for the .NET fundamentals exam you should be familiar with Collections and Specialised Collections like the StringCollection Class (which represents a collection of strings).
Namespace: System.Collections.Specialized Assembly: System.dll
C# [SerializableAttribute] public class StringCollection : IList, ICollection, IEnumerable
This class implements the IList interface, lists are a common data structure in computer science:
In computer science, a list or sequence is an abstract data structure that implements an ordered collection of values, where the same value may occur more than once. An instance of a list is a computer representation of the mathematical concept of a finite sequence, that is, a tuple. Each instance of a value in the list is usually called an item, entry, or element of the list; if the same value occurs multiple times, each occurrence is considered a distinct item.
Source: Wikipedia
A singly-linked list structure, implementing a list with 3 integer elements.
Source: Wikipedia
The name list is also used for several concrete data structures that can be used to implement abstract lists, especially linked lists.
The so-called static list structures allow only inspection and enumeration of the values. A mutable or dynamic list may allow items to be inserted, replaced, or deleted during the list's existence
Source: Wikipedia
For exam 70-536 you should be comfortable with basic code examples to create, populate and manipulate StringCollections:
StringCollection myCol = new StringCollection();
String[] myArr = new String[] { "red", "green", "blue" };
myCol.AddRange( myArr );
foreach (Object obj in myCol) Console.WriteLine("{0}", obj);
Console.WriteLine();
in the Console this returns:
red green blue
Next we can use the CopyTo method to convert our StringCollection into a String Array
String[] myArr2 = new String[myCol.Count];
myCol.CopyTo(myArr2, 0);
for (i = 0; i < myArr2.Length; i++)
{
Console.WriteLine("[{0}] {1}", i, myArr2[i]);
}
Console.WriteLine();
this returns:
[0] red [1] green [2] blue
Lastly the following shows the Add (at the end of the list) and Insert (after “position n” in list)
myCol.Add("white");
myCol.Insert(2, "gray");
foreach (Object obj in myCol) Console.WriteLine("{0}", obj);
Console.WriteLine();
this returns:
red green gray blue white
For more examples, check out MSDN sample code
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