7 Things about C#: Loops

In all of the previous articles in this series, the apps ran one time and then stopped. This is okay if the program is designed to accomplish one task and quit. However, stopping early is a problem when we want our apps to keep running until we ask them to stop.

More generally, computers are good at repetitive tasks like performing a task while a condition is true, iterating for a specific number of times, or performing a task on a list of things. This article explains how to accomplish these tasks with loops.

1 — While Loops Run on True Conditions

The If Statements tutorial discussed conditional expressions and how they are useful for determining whether to run specific logic. In a similar light, conditional expressions are important for determining whether to run specific logic in a loop. Essentially, to run code repeatedly while a condition is true. C# has a statement called a while that does just that and here’s an example:

string choice = "";

while (choice != "Q" && choice != "q")
{
  Console.WriteLine("\nDoor Chooser\n");

  Console.WriteLine("1 - Door 1");
  Console.WriteLine("2 - Door 2");
  Console.WriteLine("Q - Quit\n");

  Console.Write("Please choose (1, 2, or Q): ");

  choice = Console.ReadLine();

  Console.WriteLine("\n* You chose '{0}'", choice);
}