Conditionals and loops

Conditionals (if, else if and else) choose between paths. switch statements and the newer switch expressions pick between many cases without fall-through bugs, for example var grade = score switch { >= 90 => "A", >= 80 => "B", _ => "C" };.

Use a for loop when you need a position number, and foreach (var name in names) to walk every item. Use a while loop when you do not know the count. break leaves a loop and continue skips a pass.

Conditions must be bool (true or false), so if (count) does not compile when count is an int. That removes a class of bugs other languages have. Trace loops on paper, especially where they start and stop, because i <= list.Count throws ArgumentOutOfRangeException on the last pass.