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Simon Tatham's coroutines in C utilizes the same switch/case trick; Adam Dunkels's Protothreads - Lightweight, Stackless Threads in C also uses nested switch/case statements (see also The lightest lightweight threads, Protothreads) Pigeon's device is a related technique: intertwined switch/case and if/else statements
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 #switch function selects between multiple alternatives based on an input string. {{#switch: test string | case1 = value for case 1 | ... | default value}} Equivalent to the switch statement found in some programming languages, it is a convenient way of dealing with multiple cases without having to chain lots of #if functions together ...
Switch expressions are introduced in Java SE 12, 19 March 2019, as a preview feature. Here a whole switch expression can be used to return a value. There is also a new form of case label, case L-> where the right-hand-side is a single expression. This also prevents fall through and requires that cases are exhaustive.
Switch statements can allow compiler optimizations, such as lookup tables. In dynamic languages , the cases may not be limited to constant expressions, and might extend to pattern matching , as in the shell script example on the right, where the *) implements the default case as a glob matching any string.
Multiway branch is the change to a program's control flow based upon a value matching a selected criteria. It is a form of conditional statement.A multiway branch is often the most efficient method of passing control to one of a set of program labels, especially if an index has been created beforehand from the raw data.
The most common example of the correct use of a switch within a loop is an inversion of control such as an event handler. In event handler loops, the sequence of events is not known at compile-time, so the repeated switch is both necessary and correct (see event-driven programming , event loop and event-driven finite state machine ).
PHP has hundreds of base functions and thousands more from extensions. Prior to PHP version 5.3.0, functions are not first-class functions and can only be referenced by their name, whereas PHP 5.3.0 introduces closures. [35] User-defined functions can be created at any time and without being prototyped. [35]