# Kotlin – Calculator Program

## Kotlin – Basic Calculator

In Kotlin, you can create a simple calculator program that performs basic arithmetic operations such as addition, subtraction, multiplication, and division. This tutorial will guide you through the process of writing a Kotlin program for a basic calculator.

### Step 1: Define the Calculator Functions

Create functions for each arithmetic operation: addition, subtraction, multiplication, and division.

``````fun add(a: Double, b: Double): Double {
return a + b
}

fun subtract(a: Double, b: Double): Double {
return a - b
}

fun multiply(a: Double, b: Double): Double {
return a * b
}

fun divide(a: Double, b: Double): Double {
if (b == 0.0) {
throw IllegalArgumentException("Cannot divide by zero")
}
return a / b
}``````

### Step 2: Create the Calculator Function

Create a function that takes input for the operation type (addition, subtraction, multiplication, division) and two numbers, and then calls the corresponding calculator function.

``````fun calculate(operation: Char, a: Double, b: Double): Double {
return when (operation) {
'-' -> subtract(a, b)
'*' -> multiply(a, b)
'/' -> divide(a, b)
else -> throw IllegalArgumentException("Invalid operation")
}
}``````

### Step 3: Use the Calculator Function

Call the `calculate` function with the operation type (+, -, *, /) and two numbers, and print the result.

``````fun main() {
val operation = '+'
val num1 = 10.0
val num2 = 5.0
val result = calculate(operation, num1, num2)
println("Result of \$num1 \$operation \$num2 = \$result")
}``````

### Complete Kotlin Program

The following is the complete Kotlin program for a basic calculator.

Kotlin Program

``````fun add(a: Double, b: Double): Double {
return a + b
}

fun subtract(a: Double, b: Double): Double {
return a - b
}

fun multiply(a: Double, b: Double): Double {
return a * b
}

fun divide(a: Double, b: Double): Double {
if (b == 0.0) {
throw IllegalArgumentException("Cannot divide by zero")
}
return a / b
}

fun calculate(operation: Char, a: Double, b: Double): Double {
return when (operation) {
'-' -> subtract(a, b)
'*' -> multiply(a, b)
'/' -> divide(a, b)
else -> throw IllegalArgumentException("Invalid operation")
}
}

fun main() {
val operation = '+'
val num1 = 10.0
val num2 = 5.0
val result = calculate(operation, num1, num2)
println("Result of \$num1 \$operation \$num2 = \$result")
}``````

Output

``Result of 10.0 + 5.0 = 15.0``

## Summary

By following these steps and using functions for arithmetic operations, you can create a basic calculator program in Kotlin.