C Program to implement calculator

C Program to implement simple calculator

This c program is used to perform the simple calculator functions and continues till user quits the calculator.

Below calculator program displays menu using operators +, *, -, /, and % or q, then user has to enter the operation to perform.

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

Output:

$ cc calculator.c
$ ./a.out 

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

Enter Value 1: 4

Enter Value 2: 5

Addition of 4 and 5: 9
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
 q Quit
Enter Operation: q