Kotlin program: Calculate circle area and perimeter

Last update on February 04 2025 06:53:20 (UTC/GMT +8 hours)

Write a Kotlin program to calculate the area and perimeter of a circle.

Pre-Knowledge (Before you start!)

• Basic Kotlin Syntax.
• Kotlin Functions.
• Command-Line Arguments.
• Type Conversion.
• Mathematical Operations.
• Circle Formulas.
• Error Handling.
• String Interpolation.

Hints (Try before looking at the solution!)

• Define the main() Function.
• Prompt for Input.
• Convert Input to Number.
• Create Calculation Functions.
• Call the Functions.
• Display the Output.
• Handle Invalid Input.
• Test with Different Radii.
• Common Errors to Avoid:
  • Forgetting to validate input.
  • Misplacing operators in formulas.
  • Not handling invalid inputs gracefully.

Sample Solution:

Kotlin Code:

import kotlin.math.PI

fun main(args: Array) 
  {
    println("Input the radius of the circle:")
    val radius = args[0].toDoubleOrNull()

    if (radius != null && radius > 0) 
      {
        val area = calculateArea(radius)
        val perimeter = calculatePerimeter(radius)

        println("Radius of the circle: $radius")
        println("Area of the circle: $area")
        println("Perimeter of the circle: $perimeter")
     } 
      else 
      {
        println("Invalid input. Please enter a valid positive radius.")
     }
 }

fun calculateArea(radius: Double): Double {
    return PI * radius * radius
}

fun calculatePerimeter(radius: Double): Double {
    return 2 * PI * radius
}

Sample Output:

Input the radius of the circle:
Radius of the circle: 5.2
Area of the circle: 84.94866535306801
Perimeter of the circle: 32.67256359733385

Kotlin Editor:

Previous: Check if a year is a leap year.
Next: Kotlin Program for Celsius to Fahrenheit and Vice Versa.