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- C switch is an inbuilt statement that uses a s witch case that is prolonged if-else conditions like we have many conditions, and we need to perform different actions based on that condition. Switch case statements are used if we want a particular block of code to run only if a specific condition is satisfied.
- 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.
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.
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.
Dev C++ Switch Case Example Pdf
Syntax
The syntax for a switch statement in C programming language is as follows −
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
When the above code is compiled and executed, it produces the following result −
-->Allows selection among multiple sections of code, depending on the value of an integral expression.
Syntax
switch (
[initialization;
] expression)
{
case
constant-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
Condition | Action |
---|---|
Converted value matches that of the promoted controlling expression. | Control is transferred to the statement following that label. |
None of the constants match the constants in the case labels; a default label is present. | Control is transferred to the default label. |
None of the constants match the constants in the case labels; no default label is present. | Control is transferred to the statement after the switch statement. |
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: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.C# Switch Case Multiple
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:
Dev C++ Example Graphics Programs
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.
See also
Selection Statements
Keywords
Keywords