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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 such case it is always possible to use a function call, but this can be cumbersome and inelegant. For example, to pass conditionally different values as an argument for a constructor of a field or a base class, it is impossible to use a plain if-else statement; in this case we can use a conditional assignment expression, or a function call ...
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.
If-then-else flow diagram A nested if–then–else flow diagram. In computer science, conditionals (that is, conditional statements, conditional expressions and conditional constructs) are programming language constructs that perform different computations or actions or return different values depending on the value of a Boolean expression, called a condition.
In computer programming, indentation style is a convention, a.k.a. style, governing the indentation of blocks of source code.An indentation style generally involves consistent width of whitespace (indentation size) before each line of a block, so that the lines of code appear to be related, and dictates whether to use space or tab characters for the indentation whitespace.
The dangling else is a problem in programming of parser generators in which an optional else clause in an if–then(–else) statement can make nested conditional statements ambiguous. Formally, the reference context-free grammar of the language is ambiguous , meaning there is more than one correct parse tree .
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 ).
The following example is in the language Java, and shows how the contents of a tree of nodes (in this case describing the components of a car) can be printed. Instead of creating print methods for each node subclass ( Wheel , Engine , Body , and Car ), one visitor class ( CarElementPrintVisitor ) performs the required printing action.