Check Prime Number in Go

In this tutorial, we will learn how to check if a number is a prime number in Go. We will cover the basic concept of prime numbers and implement a function to perform the check.

What is a Prime Number

A prime number is a natural number greater than 1 that has no positive divisors other than 1 and itself. This means that a prime number cannot be formed by multiplying two smaller natural numbers.

Syntax

The syntax to check if a number is prime in Go is:

func isPrime(n int) bool {
    if n <= 1 {
        return false
    }
    for i := 2; i*i <= n; i++ {
        if n%i == 0 {
            return false
        }
    }
    return true
}

Example 1: Checking if a number is a prime number

We can create a function to check if a given number is a prime number by testing its divisors.

For example,

  1. Define a function named isPrime that takes one parameter n of type int.
  2. Check if n is less than or equal to 1. If true, return false.
  3. Use a for loop to iterate from 2 to the square root of n (inclusive).
  4. Check if n is divisible by any of the values in the loop. If true, return false.
  5. If the loop completes without finding any divisors, return true.
  6. In the main function, call the isPrime function with sample numbers and print the results.

Go Program

package main

import (
    "fmt"
)

func isPrime(n int) bool {
    if n <= 1 {
        return false
    }
    for i := 2; i*i <= n; i++ {
        if n%i == 0 {
            return false
        }
    }
    return true
}

func main() {
    // Sample numbers
    numbers := []int{2, 4, 7, 10, 13}

    // Check and print if each number is a prime number
    for _, number := range numbers {
        result := isPrime(number)
        if result {
            fmt.Printf("%d is a prime number\n", number)
        } else {
            fmt.Printf("%d is not a prime number\n", number)
        }
    }
}

Output

2 is a prime number
4 is not a prime number
7 is a prime number
10 is not a prime number
13 is a prime number