C# Tutorial 11
In this part of my C# tutorial we’ll explore many collections available with C#. We’ll look at ArrayLists, Dictionaries, Queues, and Stacks. We’ll test out most every function available with them.
For best results take notes on the heavily commented code provided below as you watch and leave any questions you have. This is the book students tell me is the best for learning C#.
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Code & Transcript
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using System; using System.Linq; // Used for ArrayLists using System.Collections; // Used for Dictionary using System.Collections.Generic; namespace CSharpTutA.cs { class Program { static void Main(string[] args) { // Collections can resize unlike arrays // #region provides a way to collapse // long blocks of code // ---------- ARRAYLISTS ---------- #region ArrayList Code // ArrayLists are resizable arrays // that can hold multiple data types ArrayList aList = new ArrayList(); aList.Add("Bob"); aList.Add(40); // Number of items in list Console.WriteLine("Count: {0}", aList.Count); // The capacity automatically increases // as items are added Console.WriteLine("Capacity: {0}", aList.Capacity); ArrayList aList2 = new ArrayList(); // Add an object array aList2.AddRange(new object[] { "Mike", "Sally", "Egg" }); // Add 1 array list to another aList.AddRange(aList2); // You can sort the list if the types // are the same aList2.Sort(); aList2.Reverse(); // Insert at the 2nd position aList2.Insert(1, "Turkey"); // Get the 1st 2 items ArrayList range = aList2.GetRange(0, 2); /* // Remove the first item aList2.RemoveAt(0); // Remove the 1st 2 items aList2.RemoveRange(0, 2); */ // Search for a match starting at the provided // index. You can also find the last index // with LastIndexOf Console.WriteLine("Turkey Index : {0}", aList2.IndexOf("Turkey", 0)); // Cycle through the list foreach (object o in range) { Console.WriteLine(o); } // Convert an ArrayList into a string array string[] myArray = (string[])aList2.ToArray(typeof(string)); // Convert a string array into an ArrayList string[] customers = { "Bob", "Sally", "Sue" }; ArrayList custArrayList = new ArrayList(); custArrayList.AddRange(customers); #endregion // ---------- DICTIONARIES ---------- #region Dictionary Code // Dictionaries store key value pairs // To create them define the data // type for the key and the value Dictionary<string, string> superheroes = new Dictionary<string, string>(); superheroes.Add("Clark Kent", "Superman"); superheroes.Add("Bruce Wayne", "Batman"); superheroes.Add("Barry West", "Flash"); // Remove a key / value superheroes.Remove("Barry West"); // Number of keys Console.WriteLine("Count : {0}", superheroes.Count); // Check if a key is present Console.WriteLine("Clark Kent : {0}", superheroes.ContainsKey("Clark Kent")); // Get the value for the key and store it // in a string superheroes.TryGetValue("Clark Kent", out string test); Console.WriteLine($"Clark Kent : {test}"); // Cycle through key value pairs foreach(KeyValuePair<string, string> item in superheroes) { Console.WriteLine("{0} : {1}", item.Key, item.Value); } // Clear a dictionary superheroes.Clear(); #endregion // ---------- QUEUES ---------- #region Queue Code // Queue 1st in 1st Out Collection // Create a Queue Queue queue = new Queue(); // Add values queue.Enqueue(1); queue.Enqueue(2); queue.Enqueue(3); // Is item in queue Console.WriteLine("1 in Queue : {0}", queue.Contains(1)); // Remove 1st item from queue Console.WriteLine("Remove 1 : {0}", queue.Dequeue()); // Look at 1st item but don't remove Console.WriteLine("Peek 1 : {0}", queue.Peek()); // Copy queue to array object[] numArray = queue.ToArray(); // Print array Console.WriteLine(string.Join(",", numArray)); // Print queue items foreach (object o in queue) { Console.WriteLine($"Queue : {o}"); } // Clear the queue queue.Clear(); #endregion // ---------- STACKS ---------- #region Queue Code // Stack Last in 1st Out Collection // Create a stack Stack stack = new Stack(); // Put items on the stack stack.Push(1); stack.Push(2); stack.Push(3); // Get but don't remove item Console.WriteLine("Peek 1 : {0}", stack.Peek()); // Remove item Console.WriteLine("Pop 1 : {0}", stack.Pop()); // Does item exist on stack Console.WriteLine("Contain 1 : {0}", stack.Contains(1)); // Copy stack to array object[] numArray2 = stack.ToArray(); // Print array Console.WriteLine(string.Join(",", numArray2)); // Print the stack foreach (object o in stack) { Console.WriteLine($"Stack : {o}"); } // Clear stack #endregion Console.ReadLine(); } } } |
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