Question

Task 2.5: A simple calculator (25 marks)

In this task you will develop a MARIE program that implements four basic functions of a calculator: addition, subtraction, multiplication, division, and exponent.

The program should be performing the user selected tasks (one of the mentioned mathematical operations) after the user enters one of the selection inputs, ‘a’, ‘s’, ‘m’, ‘d’ or ‘p’. Here, input ‘a’ selects addition process, ‘s’ selects subtraction process, ‘m’ selects multiplication process, ‘d’ selects division process, and ‘p’ selects exponent process. User enters ‘q’ to quit the program.

You are required to write subroutines to perform these tasks (addition, subtraction, multiplication, division, and power) and write a main program to process user selection inputs and call the appropriate subroutine thereof. The codes must contain comments, as a paragraph before any block of code i.e. subroutine or as inline comments wherever appropriate.

The calculator needs to be able to handle negative inputs.

Answer 1

#include<stdio.h>
#include<stdlib.h>//use of exit function
#include<math.h>//for predefined mathematical functions
//subroutine for addition
void add(int a,int b)//it takes two arguments as input
{
   printf("%d\n",a+b);//result
}
//subroutine for subtraction
void sub(int a,int b)
{
   printf("%d\n",a-b);
}
//subroutine for multiplication
void mul(int a,int b)
{
   printf("%d\n",a*b);
}
//subroutine for division
void division(int a,int b)
{
   printf("%d\n",a/b);
}
//subroutine for power
void power(int a,int b)
{
   double res;
   res=pow(a,b);
   printf("%lf\n",res);//power function
}
//main program
int main()
{
   char ch,ch1;
   int x,y;
   double f1,f2;//for power function inputs should be double datatype
   printf("user! enter the choice\n");
   printf(" a-addition\n s-subtraction\n m-multiplication\n d-division\n p-exponent\n q-quit\n");
   while(1)
   {
       scanf("%c",&ch);
       switch(ch)
       {
       case 'a':printf("Enter input values");
               scanf("%d%d",&x,&y);
               add(x,y);
               break;
       case 's':printf("Enter input values");
                   scanf("%d%d",&x,&y);
                   sub(x,y);
                   break;
       case 'm':printf("Enter input values");
                   scanf("%d%d",&x,&y);
                   mul(x,y);
                   break;
       case 'd':printf("Enter input values");
                   scanf("%d%d",&x,&y);
                   division(x,y);
                   break;
       case 'p':printf("Enter input values");
                   scanf("%d%d",&f1,&f2);
                   power(x,y);
                   break;
       case 'q':exit(0);
       }
   }
}

/*Output:
user! enter the choice
a-addition
s-subtraction
m-multiplication
d-division
p-exponent
q-quit
a
Enter input values2 3
5
s
Enter input values
3 4
-1
m
Enter input values4 5
20
d
Enter input values6 3
2
p
Enter input values4 16
216.000000
q*/