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• Dev C++ Switch Case Example List
• Switch C++ Examples
• Dev C++ Switch Case Example Diagram

Allows selection among multiple sections of code, depending on the value of an integral expression.

May 12, 2017  Switch case statements are a substitute for long if statements that compare a variable to several integral values. The switch statement is a multiway branch statement. The switch statement in C is a control statement that is useful in a limited number of cases. The switch statement resembles a compound if statement by including a number of different possibilities rather than a single test: The value of expression must be an integer (int, long, or char).

Syntax

switch ( [initialization;] expression)
{
caseconstant-expression:statement
[default :statement]
}

Remarks

The expression must have an integral type, or be a class type that has an unambiguous conversion to integral type. Integral promotion takes place as described in Standard conversions.

The switch statement body consists of a series of case labels and an optional default label. Collectively, the statements that follow the labels are called labeled statements. The labeled statements aren't syntactic requirements, but the switch statement is meaningless without them. No two constant expressions in case statements may evaluate to the same value. The default label may appear only once. The default statement is often placed at the end, but it can appear anywhere in the body of the switch statement. A case or default label can only appear inside a switch statement.

The constant-expression in each case label is converted to the type of expression. Then, it's compared with expression for equality. Control passes to the statement whose caseconstant-expression matches the value of expression. The resulting behavior is shown in the following table.

Switch statement behavior

If a matching expression is found, execution can continue through later case or default labels. The break statement is used to stop execution and transfer control to the statement after the switch statement. Without a break statement, every statement from the matched case label to the end of the switch, including the default, is executed. For example:

Dev C++ Switch Case Example List

In the above example, uppercase_A is incremented if c is an uppercase 'A'. The break statement after uppercase_A++ terminates execution of the switch statement body and control passes to the while loop. Without the break statement, execution would 'fall through' to the next labeled statement, so that lowercase_a and other would also be incremented. A similar purpose is served by the break statement for case 'a'. If c is a lowercase 'a', lowercase_a is incremented and the break statement terminates the switch statement body. If c isn't an 'a' or 'A', the default statement is executed.

Visual Studio 2017 and later: (available with /std:c++17) The [[fallthrough]] attribute is specified in the C++17 standard. You can use it in a switch statement. It's a hint to the compiler, or anyone who reads the code, that fall-through behavior is intentional. The Microsoft C++ compiler currently doesn't warn on fallthrough behavior, so this attribute has no effect on compiler behavior. In the example, the attribute gets applied to an empty statement within the unterminated labeled statement. In other words, the semicolon is necessary.

Visual Studio 2017 version 15.3 and later (available with /std:c++17). A switch statement may have an initialization clause. It introduces and initializes a variable whose scope is limited to the block of the switch statement:

An inner block of a switch statement can contain definitions with initializations as long as they're reachable, that is, not bypassed by all possible execution paths. Names introduced using these declarations have local scope. For example:

A switch statement can be nested. When nested, the case or default labels associate with the closest switch statement that encloses them.

Microsoft-specific behavior

Microsoft C doesn't limit the number of case values in a switch statement. The number is limited only by the available memory. ANSI C requires at least 257 case labels be allowed in a switch statement.

The default for Microsoft C is that the Microsoft extensions are enabled. Use the /Za compiler option to disable these extensions.

Switch C++ Examples

See also

Dev C++ Switch Case Example Diagram

Selection Statements
Keywords