Make a Simple Calculator Using switch...case in C Program

In this program takes an arithmetic operator +, -, *, / and two operands from the user and performs the calculation on the two operands depending upon the operator entered by the user.

Example: Simple Calculator using switch Statement

// Performs addition, subtraction, multiplication or division depending the input from user

# include <stdio.h>

int main() {

    char operator;
    double firstNumber,secondNumber;

    printf("Enter an operator (+, -, *,): ");
    scanf("%c", &operator);

    printf("Enter two operands: ");
    scanf("%lf %lf",&firstNumber, &secondNumber);

    switch(operator)
    {
        case '+':
            printf("%.1lf + %.1lf = %.1lf",firstNumber, secondNumber, firstNumber+secondNumber);
            break;

        case '-':
            printf("%.1lf - %.1lf = %.1lf",firstNumber, secondNumber, firstNumber-secondNumber);
            break;

        case '*':
            printf("%.1lf * %.1lf = %.1lf",firstNumber, secondNumber, firstNumber*secondNumber);
            break;

        case '/':
            printf("%.1lf / %.1lf = %.1lf",firstNumber, secondNumber, firstNumber/firstNumber);
            break;

        // operator doesn't match any case constant (+, -, *, /)
        default:
            printf("Error! operator is not correct");
    }
    
    return 0;
}

Output

Enter an operator (+, -, *,): *
Enter two operands: 1.5
4.5
1.5 * 4.5 = 6.8

The * operator entered by the user is stored in operator variable. And, the two operands, 1.5 and 4.5 are stored in variable firstNumber and secondNumber respectively.

Then, control of the program jumps to

printf("%.1lf * %.1lf = %.1lf",firstNumber, secondNumber, firstNumber*secondNumber);

This statement calculates the product and displays it on the screen.

Finally, the break; statement ends the switch statement.