Kotlin program to check if a number is prime

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In this article, you will learn how to check if a number is prime. This is done using for in Kotlin.-Loop completed.

Example1: Using for-Loop to check prime numbers

fun main(args: Array<String>) {
　　　　val num =　29
　　　　var flag = false
　　　　for (i in　2..num　/　2) {
　　　　　　　　//Condition for non-prime numbers
　　　　　　　　if (num % i == 0) {
　　　　　　　　　　　　flag = true
　　　　　　　　　　　　break
　　　　　　　　}
　　　　}
　　　　if (!flag)
　　　　　　　　println("$num is a prime number.")
　　　　else
　　　　　　　　println("$num is not a prime number.")
}

When running the program, the output is:

29　is prime.

Like Java, in the above program, the for loop is used to determine if the given number num is a prime number.

In the for loop, we check if this number can be divided by a given range (2..num/2Any number divides num. If so, flag is set to true, and we exit the loop. This determines that num is not a prime number.

　If num cannot be divided by any number, then flag is false, and num is a prime number.

The following is equivalent Java code:Java program to check for prime numbers

Example2: Program to check prime numbers using while loop

fun main(args: Array<String>) {
　　　　val num =　33
　　　　var i =　2
　　　　var flag = false
　　　　while (i <= num　/　2) {
　　　　　　　　//Condition for non-prime numbers
　　　　　　　　if (num % i == 0) {
　　　　　　　　　　　　flag = true
　　　　　　　　　　　　break
　　　　　　　　}
　　　　　　　　++i
　　　　}
　　　　if (!flag)
　　　　　　　　println("$num is a prime number.")
　　　　else
　　　　　　　　println("$num is not a prime number.")
}

When running the program, the output is:

33　Not a Prime Number

　In the above program, replace the for loop with a while loop. The loop will continue to run until i<=num/2. In each iteration, check if num can be divided by i, and increment the value of i1.

Visit this page to learn howDisplay All Prime Numbers Between Two Time Intervals.

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