C Program For A Simple Calculator

This example program accepts two input numbers and performs an arithmetic operation such as addition, subtraction, division, multiplication and mod operation on them. The output is printed to the console.

Learn following C programming concepts before trying this example on your computer.

• C Assignment Operators
• C Variables and Constants
• C Flow Control Structures
• C Functions

Program Definition

This calculator program is built using C arithmetic operators. The user is presented with a list of choices. Once the user input his or her choice that operation is performed.

Here is the list of operations presented to the users.

1. Addition
2. Subtraction
3. Multiplication
4. Division
5. Modulo
6. Close

The C calculator is implemented using the switch-case mechanism of C language.

Flowchart

Program Code

/* Program for a simple calculator 
in C using Switch_Case */
#include <stdio.h>
#include <conio.h>
main()
{
/* Variable declarations */
        int i,a,b,choice,result;
        void menu(int a,int b,int choice);
        printf("ENTER TWO NUMBERS:n");
        printf("a=:");
        scanf("%d",&a);
        printf("b=:");
        scanf("%d",&b);
        i=0;
        while(choice != 6)
        {
            menu(a,b,choice);
            i++;
        }
        getch();
        return 0;
}
void menu(int a, int b, int choice)
{
        int result,i;
        for(i=0;i < 35;i++)
        printf("*"); printf("\n\n");
        printf("\tC CALCULATOR\n\n");
        for(i=0;i < 35;i++)
        printf("_"); printf("\n\n");
        printf("1.ADDITION\n");
        printf("2.SUBTRACTION\n");
        printf("3.MULTIPLICATION\n");
        printf("4.DIVISION\n");
        printf("5.MODULO \n");
        printf("6.CLOSE\n");
        for(i=0;i < 35;i++)
        printf("_"); printf("\n\n");
        printf("Enter your Choice\n");
        scanf("%d",&choice);
        switch(choice)
        {
        case 1:
            result = a + b;
            for(i=0;i < 35;i++)
            printf("_"); printf("\n\n");
            printf("Result=%d\n",result);
/* Addition Operation */
            printf("\n\n");
            break;
        case 2:
            result = a - b;
            for(i=0;i < 35;i++)
            printf("_"); printf("\n\n");
            printf("Result=%d\n",result); 
/* Subtraction */
            printf("\n\n");
            break;
        case 3:
            result = a * b;
            for(i=0;i < 35;i++)
            printf("_"); printf("\n\n");
            printf("Result=%d\n",result); 
/* Multiplication */
            break;
        case 4:
            result = a/b;
            for(i=0;i < 35;i++)
            printf("_"); printf("\n\n");
            printf("Result=%d\n",result); 
/* Division operation */
            printf("\n\n");
            break;
        case 5:
            result = a % b;
            for(i=0;i < 35;i++)
            printf("_"); printf("\n\n");
            printf("Result=%d\n",result); 
/* Modulo operation */
            printf("\n\n");
            break;
            default:
            exit(0);
    }
}

Each arithmetic operator performs their respective operation on user inputs and return the results. Here is the list of important expressions used in the program.

result = a + b;
result = a - b;
result = a * b;
result = a / b;
result = a % b;

Output

The calculator program shows options when you run it. Enter two input numbers and then enter your choice of arithmetic operation.

ENTER TWO NUMBERS:
a=:33
b=:55
****************************************
               C CALCULATOR
________________________________________
1.ADDITION
2.SUBTRACTION
3.MULTIPLICATION
4.DIVISION
5.MODULO
6.CLOSE
________________________________________

Enter your Choice
_

The output will be displayed on the screen.

                C CALCULATOR
___________________________________________________
1.ADDITION
2.SUBTRACTION
3.MULTIPLICATION
4.DIVISION
5.MODULO
6.CLOSE
___________________________________________________
Enter your Choice
1
___________________________________________________
Result=88