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Program to Print First n Prime Numbers using For loop

Program to Print First n Prime Numbers using For loop

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  • Write a program to Print First n Prime Numbers using For loop in C
  • Write a program to Print First n Prime Numbers using For loop in C++
  • Write a program to Print First n Prime Numbers using For loop in Python
  • Write a program to Print First n Prime Numbers using For loop in PHP
  • Write a program to Print First n Prime Numbers using For loop in Java
  • Write a program to Print First n Prime Numbers using For loop in Java Script
  • Write a program to Print First n Prime Numbers using For loop in C#

Explanation:

To print the first n prime numbers using a for loop, we need to:

Steps:

  • Take input for n (the number of prime numbers to print).
  • Prime number check: To check if a number i is prime:
  • A number is prime if it is greater than 1 and divisible only by 1 and itself.
  • For each candidate number, check if it is divisible by any number from 2 to sqrt(i).
  • Loop to print the first n prime numbers:
  • Start from 2 and continue until we find n prime numbers.


Logic:

  • Iterate through numbers starting from 2 (the smallest prime number).
  • For each number, check if it is prime.
  • If it is prime, print it and count the prime numbers printed so far.
  • Stop when n prime numbers are found.

Explanation:

  • For input n = 5:
  • The program starts checking numbers from 2 (the first prime number).
  • It checks each number to see if it is prime and prints it.
  • The first 5 prime numbers are 2, 3, 5, 7, and 11

Optimization Note:

  • By checking divisibility only up to sqrt(num), the program reduces unnecessary checks for larger divisors and increases efficiency.

Program to Print First n Prime Numbers using For loop

#include <stdio.h>

int is_prime(int num) {
    for (int i = 2; i * i <= num; i++) {
        if (num % i == 0) {
            return 0;  // Not prime
        }
    }
    return 1;  // Prime
}

int main() {
    int n, count = 0, num = 2;

    printf("Enter the number of prime numbers to print: ");
    scanf("%d", &n);

    printf("First %d prime numbers are:\n", n);

    while (count < n) {
        if (is_prime(num)) {
            printf("%d ", num);
            count++;
        }
        num++;
    }

    return 0;
}

#include <iostream>
using namespace std;

bool is_prime(int num) {
    for (int i = 2; i * i <= num; i++) {
        if (num % i == 0) {
            return false;  // Not prime
        }
    }
    return true;  // Prime
}

int main() {
    int n, count = 0, num = 2;

    cout << "Enter the number of prime numbers to print: ";
    cin >> n;

    cout << "First " << n << " prime numbers are:" << endl;

    while (count < n) {
        if (is_prime(num)) {
            cout << num << " ";
            count++;
        }
        num++;
    }

    return 0;
}

def is_prime(num):
    for i in range(2, int(num ** 0.5) + 1):
        if num % i == 0:
            return False  # Not prime
    return True  # Prime

n = int(input("Enter the number of prime numbers to print: "))
count = 0
num = 2

print(f"First {n} prime numbers are:")

while count < n:
    if is_prime(num):
        print(num, end=" ")
        count += 1
    num += 1


<?php
function is_prime($num) {
    for ($i = 2; $i * $i <= $num; $i++) {
        if ($num % $i == 0) {
            return false;  // Not prime
        }
    }
    return true;  // Prime
}

$n = (int)readline("Enter the number of prime numbers to print: ");
$count = 0;
$num = 2;

echo "First $n prime numbers are:\n";

while ($count < $n) {
    if (is_prime($num)) {
        echo "$num ";
        $count++;
    }
    $num++;
}
?>


import java.util.Scanner;

public class FirstNPrimes {
    public static boolean isPrime(int num) {
        for (int i = 2; i * i <= num; i++) {
            if (num % i == 0) {
                return false;  // Not prime
            }
        }
        return true;  // Prime
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter the number of prime numbers to print: ");
        int n = scanner.nextInt();
        int count = 0, num = 2;

        System.out.println("First " + n + " prime numbers are:");

        while (count < n) {
            if (isPrime(num)) {
                System.out.print(num + " ");
                count++;
            }
            num++;
        }
        
        scanner.close();
    }
}


function isPrime(num) {
    for (let i = 2; i * i <= num; i++) {
        if (num % i === 0) {
            return false;  // Not prime
        }
    }
    return true;  // Prime
}

let n = parseInt(prompt("Enter the number of prime numbers to print:"));
let count = 0;
let num = 2;

console.log(`First ${n} prime numbers are:`);

while (count < n) {
    if (isPrime(num)) {
        console.log(num);
        count++;
    }
    num++;
}


using System;

class Program {
    static bool IsPrime(int num) {
        for (int i = 2; i * i <= num; i++) {
            if (num % i == 0) {
                return false;  // Not prime
            }
        }
        return true;  // Prime
    }

    static void Main() {
        Console.Write("Enter the number of prime numbers to print: ");
        int n = int.Parse(Console.ReadLine());
        int count = 0, num = 2;

        Console.WriteLine($"First {n} prime numbers are:");

        while (count < n) {
            if (IsPrime(num)) {
                Console.Write(num + " ");
                count++;
            }
            num++;
        }
    }
}

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