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Switch statements function somewhat similarly to the if statement used in programming languages like C/C++, C#, Visual Basic .NET, Java and exist in most high-level imperative programming languages such as Pascal, Ada, C/C++, C#, [1]: 374–375 Visual Basic .NET, Java, [2]: 157–167 and in many other types of language, using such keywords as ...
Duff's device provides a compact loop unrolling by using the case keyword both inside and outside the loop. This is unusual because the contents of a case statement are traditionally thought of as a block of code nested inside the case statement, and a reader would typically expect it to end before the next case statement.
The switch keyword is used in conjunction with case and default to create a switch statement, which evaluates a variable, matches its value to a specific case (including patterns), and executes the block of statements associated with that case. If no case matches the value, the optional block labelled by default is executed, if included.
Switch statements (or case statements, or multiway branches) compare a given value with specified constants and take action according to the first constant to match. There is usually a provision for a default action ("else", "otherwise") to be taken if no match succeeds. Switch statements can allow compiler optimizations, such as lookup tables.
The switch parser function, coded as "#switch", selects the first matching branch in a list of choices, acting as a case statement. Each branch can be a value , an expression ( calculation ), or a template call, [ 1 ] evaluated and compared to match the value of the switch.
The loop-switch sequence is a specific derivative of spaghetti code. It is not necessarily an antipattern to use a switch statement within a loop—it is only considered incorrect when used to model a known sequence of steps. The most common example of the correct use of a switch within a loop is an inversion of control such as
switch: In C#, the switch statement also operates on strings and longs. Fallthrough is allowed for empty statements and possible via 'goto case' for statements containing code. Java's switch statement operates on strings (since Java 7) but not the long primitive type, and falls through for all statements (excluding those with ' break '). [49 ...
The more complex case is a Decorator Pattern that by using interfaces, forwarding can be made more flexible and typesafe. "Flexibility" here means that C need not refer to A or B in any way, as the switching of forwarding is abstracted from C. In this example, class C can forward to any class that implements an interface I.