C switch case

C switch case

In c programming, switch case is used to perform the different logic's based on different output values of an expression.

switch case is used to reduce the complexity of using multiple if else statements.

We can have a separate logic for each case in switch, if switch expression output matches any of the case, then particular case logic will be executed. if no case matched, default block will be executed.

switch case syntax ,

switch(expression)
{
  case:
  // logic 1;
  break;
  case:
  // logic 2;
  break;
  ------------
  ------------
  default:
  // logic-default  
}

C Program for calculator using switch case

This c program is used to perform arithmetic calculations based on user input operation.

#include<stdio.h>                                                              
                                                                                
void main()                                                                     
{                                                                               
  int val1, val2;                                                               
  char op;                                                                                                                                     
  printf("\nCalculator");                                                       
  printf("\n--------------");                                                   
  printf("\n + Add\n * Multiplication\n - Subtraction\n / Division\n % Modulus");
  printf("\nEnter Operation: ");                                                
  scanf("%c", &op);                                                             
  printf("\nEnter Value 1: ");                                                  
  scanf("%d", &val1);                                                           
  printf("\nEnter Value 2: ");                                                  
  scanf("%d", &val2);                                                           
  switch(op)                                                                    
  {                                                                             
   case '+':                                                                    
     printf("Addition of %d and %d: %d", val1, val2, val1+val2);                
     break;                                                                     
   case '*':                                                                    
     printf("Multiplication of %d and %d: %d", val1, val2, val1*val2);          
     break;                                                                     
   case '-':                                                                    
     printf("Subtraction of %d and %d: %d", val1, val2, val1-val2);             
     break;                                                                     
   case '/':                                                                    
     printf("Division of %d and %d: %d", val1, val2, val1/val2);                
     break;                                                                     
   case '%':                                                                    
     printf("Modulo of %d and %d: %d", val1, val2, val1%val2);                  
     return;                                                                    
   default:                                                                     
     printf("\nInvalid operator!");                                             
   }                                                                            
                                                                                
}

Output:

$ cc switch.c
$ ./a.out 

Calculator
--------------
 + Add
 * Multiplication
 - Subtraction
 / Division
 % Modulus
Enter Operation: +

Enter Value 1: 23

Enter Value 2: 12
Addition of 23 and 12: 35
$ ./a.out 

Calculator
--------------
 + Add
 * Multiplication
 - Subtraction
 / Division
 % Modulus
Enter Operation: *

Enter Value 1: 2

Enter Value 2: 6
Multiplication of 2 and 6: 12
$ ./a.out 

Calculator
--------------
 + Add
 * Multiplication
 - Subtraction
 / Division
 % Modulus
Enter Operation: -

Enter Value 1: 6

Enter Value 2: 3
Subtraction of 6 and 3: 3
$ ./a.out 

Calculator
--------------
 + Add
 * Multiplication
 - Subtraction
 / Division
 % Modulus
Enter Operation: /

Enter Value 1: 25

Enter Value 2: 5
Division of 25 and 5: 5
$ ./a.out 

Calculator
--------------
 + Add
 * Multiplication
 - Subtraction
 / Division
 % Modulus
Enter Operation: %

Enter Value 1: 7

Enter Value 2: 4
Modulo of 7 and 4: 3
$ ./a.out 

Calculator
--------------
 + Add
 * Multiplication
 - Subtraction
 / Division
 % Modulus
Enter Operation: $

Enter Value 1: e

Enter Value 2: 
Invalid operator!

What will happen if you are not using break in each case ?

C switch case with no break

#include<stdio.h>                                                             
                                                                                
void main()                                                                     
{                                                                               
  int val1, val2;                                                               
  char op;                                                                                                                                         
  printf("\nCalculator");                                                       
  printf("\n--------------");                                                   
  printf("\n + Add\n * Multiplication\n - Subtraction\n / Division\n % Modulus");
  printf("\nEnter Operation: ");                                                
  scanf("%c", &op);                                                             
  printf("\nEnter Value 1: ");                                                  
  scanf("%d", &val1);                                                           
  printf("\nEnter Value 2: ");                                                  
  scanf("%d", &val2);                                                           
  switch(op)                                                                    
  {                                                                             
   case '+':                                                                    
     printf("\nAddition of %d and %d: %d", val1, val2, val1+val2);              
   case '*':                                                                    
     printf("\nMultiplication of %d and %d: %d", val1, val2, val1*val2);        
   case '-':                                                                    
     printf("\nSubtraction of %d and %d: %d", val1, val2, val1-val2);           
   case '/':                                                                    
     printf("\nDivision of %d and %d: %d", val1, val2, val1/val2);              
   case '%':                                                                    
     printf("\nModulo of %d and %d: %d", val1, val2, val1%val2);                
   default:                                                                     
     printf("\nInvalid operator!");                                             
   }                                                                            
                                                                                
}        

Output:

$ cc switch.c
$ ./a.out 

Calculator
--------------
 + Add
 * Multiplication
 - Subtraction
 / Division
 % Modulus
Enter Operation: +

Enter Value 1: 5

Enter Value 2: 4

Addition of 5 and 4: 9
Multiplication of 5 and 4: 20
Subtraction of 5 and 4: 1
Division of 5 and 4: 1
Modulo of 5 and 4: 1
Invalid operator!

$ ./a.out 

Calculator
--------------
 + Add
 * Multiplication
 - Subtraction
 / Division
 % Modulus
Enter Operation: -

Enter Value 1: 5

Enter Value 2: 2

Subtraction of 5 and 2: 3
Division of 5 and 2: 2
Modulo of 5 and 2: 1
Invalid operator!