# Kotlin Program to Make a Simple Calculator Using switch...case

In this program, you'll learn to make a simple calculator using when expression in Kotlin. This calculator would be able to add, subtract, multiply and divide two numbers.

## Example: Simple Calculator using switch Statement

``````import java.util.*

fun main(args: Array<String>) {
val reader = Scanner(System.`in`)
print("Enter two numbers: ")

// nextDouble() reads the next double from the keyboard
val first = reader.nextDouble()
val second = reader.nextDouble()

print("Enter an operator (+, -, *, /): ")
val operator = reader.next()

val result: Double

when (operator) {
'+' -> result = first + second
'-' -> result = first - second
'*' -> result = first * second
'/' -> result = first / second
// operator doesn't match any case constant (+, -, *, /)
else -> {
System.out.printf("Error! operator is not correct")
return
}
}

System.out.printf("%.1f %c %.1f = %.1f", first, operator, second, result)
}``````

When you run the program, the output will be:

```Enter two numbers: 1.5
4.5
Enter an operator (+, -, *, /): *
1.5 * 4.5 = 6.8```

The `*` operator entered by the user is stored in the operator variable using the `next()` method of `Scanner` object.

Likewise, the two operands, 1.5 and 4.5 are stored in variables first and second respectively using the `nextDouble()` method of `Scanner` object.

Since, the operator `*` matches the when condition `'*':`, the control of the program jumps to

```result = first * second;
```

This statement calculates the product and stores in the variable result and it is printed using the `printf` statement.

Here's the equivalent Java code: Java Program to Make a Simple Calculator