The switch case statement is used when we have multiple options and we need to perform a different task for each option.
Switch Case Statement in C
The switch statement in C is an alternate to if-else-if ladder statement which allows us to execute multiple operations for the different possibles values of a single variable called switch variable. Here, We can define various statements in the multiple cases for the different values of a single variable.
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.
Before we see how a switch case statement works in a C program, let’s checkout the syntax of it.
switch (variable or an integer expression)
{
case constant:
//C Statements
;
case constant:
//C Statements
;
default:
//C Statements
;
}
How does the switch statement work?
The expression is evaluated once and compared with the values of each case label.
If there is a match, the corresponding statements after the matching label are executed. For example, if the value of the expression is equal to constant2, statements after case constant2: are executed until break is encountered.
If there is no match, the default statements are executed.
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.
Let's see a simple example of c language switch statement.
int main()
{
int number ;
printf("enter a number:");
scanf("%d",&number);
switch (number) {
case 1:
printf(" Your Choice is 1");
break;
case 2:
printf("Your Choice is 2");
break;
case 3:
printf("Your Choice is 3");
break;
default:
printf("Not Available");
break;
}
return 0;
}
Output:
enter a number:2
Your Choice is 2
C Switch statement is fall-through
In C language, the switch statement is fall through; it means if you don't use a break statement in the switch case, all the cases after the matching case will be executed.
