C# Tutorial 3
In this part of my C# tutorial we’ll cover If, Else, Else If, Relational Operators, Logical Operators, Ternary Operator, Switch, Break, Continue, Goto, While Do While, Convert, Try, Catch, Finally and Exception Handling.
Like always all of the code and a transcript of the video follows the video below. Print out the code and take notes as you watch for best results.
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Code & Transcript
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using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace CSharpTutA.cs { class Program { static void Main(string[] args) { // ----- CONDITIONALS ----- // ----- IF / ELSE / ----- // Relational Operators : > < >= <= == != // Logical Operators : && || ! int age = 17; if ((age >= 5) && (age <= 7)) { Console.WriteLine("Go to elementary school"); } else if ((age > 7) && (age < 13)) { Console.WriteLine("Go to middle school"); } else if ((age > 13) && (age < 19)) { Console.WriteLine("Go to high school"); } else { Console.WriteLine("Go to college"); } if ((age < 14) || (age > 67)) { Console.WriteLine("You shouldn't work"); } Console.WriteLine("! true = " + (!true)); // Ternary Operator // Assigns the 1st value if true and otherwise // the 2nd bool canDrive = age >= 16 ? true : false; // Switch is used when you have limited options // The only way to use ranges is to stack // the possible values switch (age) { case 1: case 2: Console.WriteLine("Go to Day Care"); break; case 3: case 4: Console.WriteLine("Go to Preschool"); break; case 5: Console.WriteLine("Go to Kindergarten"); break; default: Console.WriteLine("Go to another school"); // You can also jump out of a switch // with goto goto OtherSchool; } OtherSchool: Console.WriteLine("Elementary, Middle, High School"); // To compare strings use Equals string name = "Derek"; string name2 = "Derek"; if (name.Equals(name2, StringComparison.Ordinal)) { Console.WriteLine("Names are Equal"); } // ----- WHILE LOOP ----- // You use the while loop when you want to execute // as long as a condition is true // This while loop will print odd numbers between // 1 and 10 int i = 1; while (i <= 10) { // % (Modulus) returns the remainder of a // division. If it returns 0 that means the // value is even if (i % 2 == 0) { i++; // Continue skips the rest of the code and // starts execution back at the top of the // while continue; } // Break jumps completely out of the loop if (i == 9) break; Console.WriteLine(i); i++; } // ----- DO WHILE LOOP ----- // Use do while when you must execute the code // at least once // Generate a random number Random rnd = new Random(); int secretNumber = rnd.Next(1, 11); int numberGuessed = 0; do { Console.Write("Enter a number between 1 & 10 : "); // Use Convert to switch the string into an int numberGuessed = Convert.ToInt32(Console.ReadLine()); } while (secretNumber != numberGuessed); Console.WriteLine("You guessed it is was {0}", secretNumber); // Other Convert options : ToBoolean, ToByte, // ToChar, ToDecimal, ToDouble, ToInt64, // ToString, and they can convert from any // type to any other type // ----- EXCEPTION HANDLING ----- // We use exception handling to catch errors // that could crash our program double num1 = 5; double num2 = 0; // Code that could cause an error is surrounded // by a try block try { Console.WriteLine("5 / 0 = {0}", DoDivision(num1, num2)); } // We catch the error and warn the user // rather then crash the program catch (DivideByZeroException ex) { Console.WriteLine("You can't Divide by Zero"); // Get additonal info on the exception Console.WriteLine(ex.GetType().Name); Console.WriteLine(ex.Message); } // This is the default catch all for exceptions catch (Exception ex) { Console.WriteLine("An error occurred"); Console.WriteLine(ex.GetType().Name); Console.WriteLine(ex.Message); } // finally always runs and provides for clean up finally { Console.WriteLine("Cleaning Up"); } // Well cover more about exception handling // with some real examples soon Console.ReadLine(); } static double DoDivision(double x, double y) { if(y == 0) { // We are throwing an exception because // you can't divide by zero throw new System.DivideByZeroException(); } return x / y; } } } |
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