C# Tutorial 16
In this part of my C# tutorial I’ll cover threads in depth. With threads you can execute multiple pieces of code that share resources and data without corrupting it. I cover a simple thread example, sleep, a more advanced with lock, Priority, and how to pass data to a thread.
For best results take notes on the cheat sheet provided above as you watch and leave any questions you have.
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Code & Transcript
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using System; using System.Linq; using System.Collections; using System.Collections.Generic; using System.Threading; namespace CSharpTutA.cs { // With threads you can execute multiple // pieces of code that share resources // and data without corrupting it // You can't guarantee when a thread // executes. You also must lock resources // until a thread is done with them // or you could corrupt them class Program { // ----- Simple Thread Example ----- /* static void Main(string[] args) { // Create a thread and start it Thread t = new Thread(Print1); t.Start(); // This code will run randomly for (int i = 0; i < 1000; i++) Console.Write(0); Console.ReadLine(); } static void Print1() { for (int i = 0; i < 1000; i++) Console.Write(1); } // ----- Sleep Example ----- // With sleep() the thread is suspended // for the designated amount of time static void Main(string[] args) { int num = 1; for (int i = 0; i < 10; i++) { Console.WriteLine(num); // Pause for 1 second Thread.Sleep(1000); num++; } Console.WriteLine("Thread Ends"); Console.ReadLine(); } // ----- Lock Example ----- // lock keeps other threads from entering // a statement block until another thread // leaves static void Main(string[] args) { BankAcct acct = new BankAcct(10); Thread[] threads = new Thread[15]; // CurrentThread gets you the current // executing thread Thread.CurrentThread.Name = "main"; // Create 15 threads that will call for // IssueWithdraw to execute for (int i = 0; i < 15; i++) { // You can only point at methods // without arguments and that return // nothing Thread t = new Thread(new ThreadStart(acct.IssueWithdraw)); t.Name = i.ToString(); threads[i] = t; } // Have threads try to execute for (int i = 0; i < 15; i++) { // Check if thread has started Console.WriteLine("Thread {0} Alive : {1}", threads[i].Name, threads[i].IsAlive); // Start thread threads[i].Start(); // Check if thread has started Console.WriteLine("Thread {0} Alive : {1}", threads[i].Name, threads[i].IsAlive); } // Get thread priority (Normal Default) // Also Lowest, BelowNormal, AboveNormal // and Highest // Changin priority doesn't guarantee // the highest precedence though // It is best to not mess with this Console.WriteLine("Current Priority : {0}", Thread.CurrentThread.Priority); Console.WriteLine("Thread {0} Ending", Thread.CurrentThread.Name); Console.ReadLine(); } } } class BankAcct { private Object acctLock = new Object(); double Balance { get; set; } string Name { get; set; } public BankAcct(double bal) { Balance = bal; } public double Withdraw(double amt) { if((Balance - amt) < 0) { Console.WriteLine($"Sorry ${Balance} in Account"); return Balance; } lock (acctLock) { if(Balance >= amt) { Console.WriteLine("Removed {0} and {1} left in Account", amt, (Balance - amt)); Balance -= amt; } return Balance; } } // You can only point at methods // without arguments and that return // nothing public void IssueWithdraw() { Withdraw(1); } } */ // ----- Passing Data to Threads ----- // You can pass arguments to a thread // using a lambda expression static void Main(string[] args) { Thread t = new Thread(() => CountTo(10)); t.Start(); // You can use multiline lambdas new Thread(() => { CountTo(5); CountTo(6); }).Start(); Console.ReadLine(); } static void CountTo(int maxNum) { for(int i = 0; i <= maxNum; i++) { Console.WriteLine(i); } } } } |
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