C Program to Make a Simple Calculator

A calculator is an electronic device that is used to perform arithmetic operations like addition, subtraction, multiplication, division, etc. We can create a simple calculator program in C to perform all these basic calculations. In this article, we will see how to create a simple calculator in C using the switch statement.

This program takes an arithmetic operator (+, -, *, /) and two operands as the input. It then checks whether the user wants to quit the program if yes then quit it, for this, we can use a special character and tell the user about it, like here we used “x”. The operation is performed based on the operator.

Approach

1. All the following steps will be performed inside a never-ending loop so that the calculator program keeps on working.
2. Take input of operator and then operands.
3. Check whether the user wants to quit the program if yes then quit it, for this, we can use a special character and tell the user about it, like here we used “x”.
4. Using if-else statements we will check operators and do operations accordingly.

Simple Calculator Program using switch Statement

Below is the C program to implement a simple calculator using a switch case statement:

C

// C Program to make a Simple Calculator
// Using switch case
#include <stdio.h>
#include <stdlib.h>

// Driver code
int main()
{
    char ch;
    double a, b;
    while (1) {
        printf("Enter an operator (+, -, *, /), "
               "if want to exit press x: ");
        scanf(" %c", &ch);

        // to exit
        if (ch == 'x')
            exit(0);
        printf("Enter two first and second operand: ");
        scanf("%lf %lf", &a, &b);

        // Using switch case we will differentiate
        // operations based on different operator
        switch (ch) {

        // For Addition
        case '+':
            printf("%.1lf + %.1lf = %.1lf\n", a, b, a + b);
            break;

        // For Subtraction
        case '-':
            printf("%.1lf - %.1lf = %.1lf\n", a, b, a - b);
            break;

        // For Multiplication
        case '*':
            printf("%.1lf * %.1lf = %.1lf\n", a, b, a * b);
            break;

        // For Division
        case '/':
            printf("%.1lf / %.1lf = %.1lf\n", a, b, a / b);
            break;

        // If operator doesn't match any case constant
        default:
            printf(
                "Error! please write a valid operator\n");
        }

        printf("\n");
    }
}

Output

Enter an operator (+, -, *, /), if want to exit press x: +
Enter two first and second operand: 7 8
7.0 + 8.0 = 15.0
Enter an operator (+, -, *, /), if want to exit press x: -
Enter two first and second operand: 8 9
8.0 - 9.0 = -1.0
Enter an operator (+, -, *, /), if want to exit press x: *
Enter two first and second operand: 8 7
8.0 * 7.0 = 56.0
Enter an operator (+, -, *, /), if want to exit press x: /
Enter two first and second operand: 8 3
8.0 / 3.0 = 2.7
Enter an operator (+, -, *, /), if want to exit press x: x

Complexity Analysis

• Time Complexity: O(1)
• Auxiliary Space: O(1)