switch statement

 

C

Language

Standard Library

Type support

Dynamic memory management

Error handling

Program utilities

Date and time utilities

Strings library

Algorithms

Numerics

Input/output support

Localization support

Thread support (C11)

Atomic operations (C11)

 

C language

General topics
Preprocessor
Comments
Keywords
Escape sequences
History of C
Flow control
Conditional execution statements
if statement	switch statement
Iteration statements
for loop	while loop do-while loop
Jump statements
continue statement break statement	goto statement return statement
Functions
function declaration
inline specifier
Types
fundamental types pointer types compound types enumeration types	union types function types
Specifiers
cv specifiers
storage-class specifiers
alignas specifier (C99)
function specifiers (C99)
Literals
integer literals character literals floating-point literals	string literals boolean literals(C99)
Expressions
order of evaluation
operators
operator precedence
alternative operators
Utilities
typedef declaration
attributes (C99)
casts
Miscellaneous
Inline assembly

 

Executes code according to value of an integral argument

Used where one or several out of many branches of code need to be executed according to an integral value.

Syntax

switch ( expression ) { case constant_expression1 : statement1 (optional) case constant_expression2 : statement2 (optional) ... ... ... case constant_expressionn : statementn (optional) default: default_statement (optional) }

Explanation

expression shall be an expression, convertible to an integer value.

All constant_expressions shall be constant expressions, convertible to an integer value, which is unique within this switch statement

If the expression evaluates to a value, equal to the value of one of the defined constant_expression_i, the statement_i (if present) and all subsequent statements (including default_statement, if present) are executed. If the value of the expression does not match any of the constant_expressions, the default_statement is executed if present.

It is useful to note, that if the execution of subsequent statements is undesirable, the break statement can be used. In that case the execution of the switch statement terminates.

Keywords

switch, case, default

Example

Run this code

#include <stdio.h>
 
void func(int x)
{
   printf("func(%d): ", x);
   switch(x)
   {
      case 1: printf("case 1, ");
 
      case 2: printf("case 2, ");
 
      case 3: printf("case 3.\n"); break;
 
      case 4: printf("case 4, ");
 
      case 5: printf("case 5, ");
 
      default: printf("default.\n");
   }
}
 
 
int main(void)
{
   for(int i = 1; i < 10; ++i)  func(i);
}

Output:

func(1): case 1, case 2, case 3.
func(2): case 2, case 3.
func(3): case 3.
func(4): case 4, case 5, default.
func(5): case 5, default.
func(6): default.
func(7): default.
func(8): default.
func(9): default.