Kotlin program: Check if a number is even or odd

Last update on February 04 2025 06:50:00 (UTC/GMT +8 hours)

Write a Kotlin program to check if a given number is even or odd.

Pre-Knowledge (Before you start!)

• Basic Kotlin Syntax.
• Kotlin Functions.
• Command-Line Arguments.
• Type Conversion.
• Conditional Statements.
• Modulo Operator.
• String Interpolation.
• Error Handling.

Hints (Try before looking at the solution!)

• Define the main() Function.
• Check for Input.
• Convert Input to Number.
• Validate Conversion.
• Check Even or Odd.
• Handle Invalid Input.
• Handle Missing Input.
• Test with Different Inputs.
• Common Errors to Avoid:
  • Forgetting to check if args is empty.
  • Not handling invalid inputs properly.
  • Misplacing operators or parentheses.

Sample Solution:

Kotlin Code:

fun main(args: Array<String>) {
    if (args.isNotEmpty()) {
        val number = args[0].toIntOrNull()
        
        if (number != null) {
            if (number % 2 == 0) {
                println("$number is even.")
            } else {
                println("$number is odd.")
            }
        } else {
            println("Invalid input. Please enter a valid number.")
        }
    } else {
        println("No input provided. Please provide a number as a command-line argument.")
    }
}

Sample Output:

12 is even.

17 is odd.

Explanation:

In the above exercise -

• Inside the "main()" function, a variable named number is declared and assigned a value of 12.
• The if statement is used to check whether number is divisible evenly by 2. The expression number % 2 calculates the remainder when number is divided by 2. If the remainder is 0, it means the number is even.
• If the condition number % 2 == 0 evaluates to true, the code block inside the if statement executes. In this case, it prints the message "$number is even." using string interpolation, where $number is replaced by the actual value of number.
• If the condition number % 2 == 0 evaluates to false, the code block inside the else statement executes. In this case, it prints the message "$number is odd." using string interpolation, where $number is replaced by the actual value of number.

Kotlin Editor:

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