switch case in C Programming Language

Switch case in C Programming

Must Read :

Switch Case
Rules of using switch
Illegal ways of Using switch
Valid Ways of using switch case
Switch case : Tricky Questions ?

Why Need arises ?

One of the classic problem encountered in nested if-else / else-if ladder is called problem of Confusion.
It occurs when no matching else is available for if .
As the number of alternatives increases the Complexity of program increases drastically.
To overcome this , C Provide a multiway decision statement called 'switch'

Syntax :

   switch ( expression )
         {
case value1 :
body1
                        break;

case value2 :
body2
                        break;

case value3 :
body3
                        break;
- - - - - - - - -
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default :
   default-body
   break;

         }
        next-statement;

How it works ?

Switch case checks the value of expression/variable against the list of case values and when the match is found , the block of statement associated with that case is executed
Expression should be Integer expression / Character
Break statement takes control out of the case.

Example and Steps of Execution :

#include<stdio.h>
#include<conio.h>
void main()
{
int roll = 3 ;
switch ( roll )
{
case 1 :
printf ( " I am Pankaj ");
break;
case 2 :
printf ( " I am Nikhil ");
break;
case 3 :
printf ( " I am John ");
break;
default :
printf ( "No student found");
break;
}
getch()
}

As explained earlier -

3 is assigned to integer variable 'roll'
As control goes to line number 6 above switch case will replace the 'roll' by 3 So temporarily line 6 changes to switch ( 3 )
This checks matching case having expression '3'
As it founds the matching case it Executes the body and output as ' I am John '
After executing the body , break takes control out of the switch case i.e line number 21
Suppose no matching case found then default case and its body is executed