Switch statement in C | My CS Tutorial

Switch statement is a conditional statement in C programming.
In this tutorial we will discuss, what is switch statement in c programming language? and procedure of switch statement to use it in a c program source code.

switch Statement

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.

Syntax

The syntax for a switch statement in C programming language is as follows:

switch(expression){
 case constant-expression :
 statement(s);
 break; /* optional */
 case constant-expression :
 statement(s);
 break; /* optional */

 /* you can have any number of case statements */
 default : /* Optional */
 statement(s);
}


The following rules apply to a switch statement:

1. 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.
2. 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.
3. 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.
4. When the variable being switched on is equal to a case, the statements following that case will execute until a break statement is reached.
5. 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.
6. 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

Flow diagram of switch statement

Example

#include <stdio.h>
int main ()
{
 /* local variable definition */
 char grade = 'B';
 switch(grade)
 {
 case 'A' :
 printf("Excellent!\n" );
 break;
 case 'B' :
 case 'C' :
 printf("Well done\n" );
 break;
 case 'D' :
 printf("You passed\n" );
 break;
 case 'F' :
 printf("Better try again\n" );
 break;
 default :
 printf("Invalid grade\n" );
 }
 printf("Your grade is %c\n", grade );
 return 0;
}


When the above code is compiled and executed, it produces the following result:

Well done
Your grade is B

Nested switch Statements

It is possible to have a switch as a part of the statement sequence of an outer
switch. Even if the case constants of the inner and outer switch contain common
values, no conflicts will arise.

Syntax

The syntax for a nested switch statement is as follows:


switch(ch1) {
 case 'A':
 printf("This A is part of outer switch" );
switch(ch2) {
 case 'A':
 printf("This A is part of inner switch" );
 break;
 case 'B': /* case code */
 }
 break;
 case 'B': /* case code */
}

Example

#include <stdio.h>
int main ()
{
 /* local variable definition */
 int a = 100;
 int b = 200;
 switch(a) {
 case 100:
 printf("This is part of outer switch\n", a );
 switch(b) {
 case 200:
 printf("This is part of inner switch\n", a );
 }
 }
 printf("Exact value of a is : %d\n", a );
 printf("Exact value of b is : %d\n", b );
 return 0;
}


When the above code is compiled and executed, it produces the following result:

This is part of outer switch
This is part of inner switch
Exact value of a is : 100
Exact value of b is : 200

The ? : Operator:

We have covered conditional operator ? : in the previous chapter which can be
used to replace if...else statements.

 It has the following general form:

Exp1 ? Exp2 : Exp3;

Where Exp1, Exp2, and Exp3 are expressions. Notice the use and placement of
the colon.

The value of a ? expression is determined like this:

1. Exp1 is evaluated. If it is true, then Exp2 is evaluated and becomes the
value of the entire ? expression.

2. If Exp1 is false, then Exp3 is evaluated and its value becomes the value of
the expression.

Please share this post and blog link with your friends.For more programs use this blog.

If you have any problem, please comment in comment box, subscribe this blog for notifications of new post on your email and follow this blog.If you have any method of this program or want to give any suggestion send email on hc78326@gmail.com

Created by-- HARSH CHAUHAN