C Switch
Switch Statement
Instead of writing many if..else statements, you can use the switch statement.
The switch statement selects one of many code blocks to be executed:
Syntax
switch (expression) {
case x:
// code
block
break;
case y:
// code block
break;
default:
// code block
}
This is how it works:
- The
switchexpression is evaluated once - The value of the expression is compared with the values of each
case - If there is a match, the associated block of code is executed
- The
breakstatement breaks out of the switch block and stops the execution - The
defaultstatement is optional, and specifies some code to run if there is no case match
The example below uses the weekday number to calculate the weekday name:
Example
int day = 4;
switch (day) {
case 1:
printf("Monday");
break;
case 2:
printf("Tuesday");
break;
case 3:
printf("Wednesday");
break;
case 4:
printf("Thursday");
break;
case 5:
printf("Friday");
break;
case 6:
printf("Saturday");
break;
case 7:
printf("Sunday");
break;
}
// Outputs "Thursday" (day 4)
Try it Yourself »
The break Keyword
When C reaches a break
keyword, it breaks out of the switch block.
This will stop the execution of more code and case testing inside the block.
When a match is found, and the job is done, it's time for a break. There is no need for more testing.
A break can save a lot of execution time because it "ignores" the execution of all the rest of the code in the switch block.
The default Keyword
The default keyword specifies some code to run if there is no
case match:
Example
int day = 4;
switch (day) {
case 6:
printf("Today is
Saturday");
break;
case 7:
printf("Today is Sunday");
break;
default:
printf("Looking forward to the Weekend");
}
// Outputs "Looking forward to the Weekend"
Try it Yourself »
Note: The default keyword must be used as the last statement in the switch, and it does not need a break.
