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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 ...
In the C programming language, Duff's device is a way of manually implementing loop unrolling by interleaving two syntactic constructs of C: the do-while loop and a switch statement. Its discovery is credited to Tom Duff in November 1983, when Duff was working for Lucasfilm and used it to speed up a real-time animation program.
Loops using while, repeat until or do, and for statements; switch a.k.a. case statements, a form of multiway branching; These new language mechanisms replaced equivalent flows which previously would have been written using gotos and ifs. Multi-way branching replaces the "computed goto" in which the instruction to jump to is determined ...
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
Within a single switch statement, the integer constant associated with each case label must be unique. There may or may not be a default statement. There is no restriction on the order of the labels within a switch. The requirement that case labels values evaluate to integer constants gives the compiler more room for optimizations.
Switch statements in Java can use byte, short, char, and int (not long) primitive data types or their corresponding wrapper types. Starting with J2SE 5.0, it is possible to use enum types. Starting with Java SE 7, it is possible to use Strings. [2] Other reference types cannot be used in switch statements. Possible values are listed using case ...
The switch statement evaluates its expression, then executes all statements that follow the matching case label; see switch. [9] [10] catch Used in conjunction with a try block and an optional finally block. The statements in the catch block specify what to do if a specific type of exception is thrown by the try block. char
To avoid potential bugs owing to the similarity of the switch statement syntax with that of C or C++, C# requires a break for each non-empty case label of a switch (unless goto, return, or throw is used) even though it does not allow implicit fall-through. [16] (Using goto and specifying the subsequent label produces a C/C++-like fall-through.)