D-Decisions-Switch Statement - D Programming Language

A switch statement allows a variable to be tested for equality against a list of values. Each value is called a case, and the variable being switched on is checked for each switch case.

Syntax:

The syntax for a switch statement in D programming language is as follows:

switch(expression){ case constant-expression : statement(s); break; /* optional */ case constant-expression : statement(s); break; /* optional */ /* you can have any number of case statements */ default : /* Optional */ statement(s); }

The following rules apply to a switch statement:

• The expression used in a switch statement must have an integral or enumerated type, or be of a class type in which the class has a single conversion function to an integral or enumerated type.
• You can have any number of case statements within a switch. Each case is followed by the value to be compared to and a colon.
• The constant-expression for a case must be the same data type as the variable in the switch, and it must be a constant or a literal.
• When the variable being switched on is equal to a case, the statements following that case will execute until a break statement is reached.
• When a break statement is reached, the switch terminates, and the flow of control jumps to the next line following the switch statement.
• Not every case needs to contain a break. If no break appears, the flow of control will fall through to subsequent cases until a break is reached.
• A switch statement can have an optional default case, which must appear at the end of the switch. The default case can be used for performing a task when none of the cases is true. No break is needed in the default case.

Flow Diagram:

Example:

import std.stdio; int main () { /* local variable definition */ char grade = 'B'; switch(grade) { case 'A' : writefln("Excellent!" ); break; case 'B' : case 'C' : writefln("Well done" ); break; case 'D' : writefln("You passed" ); break; case 'F' : writefln("Better try again" ); break; default : writefln("Invalid grade" ); } writefln("Your grade is %c", grade ); return 0; }
When the above code is compiled and executed, it produces the following result:

Well done Your grade is B