Switch Statement


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Switch Statement

The switch statement in C language is used to execute the code from multiple conditions or case. It is same like if else-if ladder statement.

A switch statement work with byte, short, char and int primitive data type, it also works with enumerated types and string.

Syntax

switch(expression or variable)
{
case  value:
//statements
// any number of case statements
break;  //optional
default: //optional
//statements
}

Flow chart

Switch Case

Rules for apply switch

  • The switch expression must be of integer or character type.
  • With switch statement use only byte, short, int, char data type.
  • With switch statement not use float data type.
  • You can use any number of case statements within a switch.
  • The case value can be used only inside the switch statement.
  • Value for a case must be same as the variable in switch.

Valid statement for switch

Example

int x;
byte y;
short z;
char a,b;

Limitations of switch

Logical operators can not be used with switch statement. For instance

Example

case k>20&&k=20:	// is not allowed

Switch case variables can have only int and char data type. So float data type is not allowed.

case 4.2:  // Invalid 

Syntax

switch(ch) 
{ 
case 1:   
statement 1; 
break; 
case 2: 
statement 2; 
break; 
} 

In this ch can be integer or char and can not be float or any other data type.

Rulse table of switch

Valid SwitchInvalid SwitchValid CaseInvalid Case
switch(a)switch(2.3)case 3;case 2.5;
switch(a>b)switch(a+2.5)case 'a';case x;
switch(a+b-2)case 1+2;case x+2;
switch(func(a,b))case 'a'>'b';case 1,2,3;

Example of switch case

#include<stdio.h>
#include<conio.h>

void main()
{
int ch;
clrscr();
printf("Enter any number (1 to 7)");
scanf("%d",&ch);
switch(ch)
{
case  1:
printf("Today is Monday");
break;
case  2:
printf("Today is Tuesday");
break;
case  3:
printf("Today is Wednesday");
break;
case  4:
printf("Today is Thursday");
break;
case  5:
printf("Today is Friday");
break;
case  6:
printf("Today is Saturday");
break;
case  7:
printf("Today is Sunday");
break;
default:
printf("Only enter value 1 to 7");
}
getch();
}

Output

Enter any number (1 to 7): 5 Today is Friday

Note: In switch statement default is optional but when we use this in switch default is executed at last whenever all cases are not satisfied the condition.

Example of Switch without break

#include<stdio.h>
#include<conio.h>

void main()
{
int ch;
clrscr();
printf("Enter any number (1 to 7)");
scanf("%d",&ch);
switch(ch)
{
case  1:
printf("Today is Monday");
case  2:
printf("Today is Tuesday");
case  3:
printf("Today is Wednesday");
case  4:
printf("Today is Thursday");
case  5:
printf("Today is Friday");
case  6:
printf("Today is Saturday");
case  7:
printf("Today is Sunday");
default:
printf("Only enter value 1 to 7");
}
getch();
}

Output

Enter any number (1 to 7): 4 Today is Thursday Today is Friday Today is Saturday Today is Sunday

Note: In switch statement when you not use break keyword after any statement then all the case after matching case will be execute. In above code case 4 is match and after case 4 all case are execute from case-4 to case-7.

C Program for calculator

Example

#include<stdio.h>
#include<conio.h>

void main()
{
char choice;
int a,b,res=0;
clrscr();
printf("Enter first value: ");
scanf("%d",&a);
printf("\n Enter operator: ");
choice=getch();
printf("\n Enter second value: ");
scanf("%d",&b);

switch(choice)
{
case '+':
  res=a+b;
  printf("Sum: %d",res);
break;
case '-':
  res=a-b;
  printf("Difference: %d",res);
break;
case '*':
  res=a*b;
  printf("Product: %d",res);
break;
case '/':
  res=a/b;
  printf("Quotient: %d",res);
break;
default:
  printf("Enter Valid Operator!!");
}
getch();
}

Example

Enter First number: 6
Enter operator : +
Enter Second number: 10
Sum: 16

Explanation: In above code choice=getch(); is used for scan or get one value by using getch() function from keyboard, and store is choice.


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