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Program to print prime numbers from 1 to N.
  • Difficulty Level : Medium
  • Last Updated : 19 Oct, 2020

Given a number N, the task is to print the prime numbers from 1 to N.
Examples: 

Input: N = 10
Output: 2, 3, 5, 7

Input: N = 5
Output: 2, 3, 5 

Approach:  

  • First, take the number N as input.
  • Then use a for loop to iterate the numbers from 1 to N
  • Then check for each number to be a prime number. If it is a prime number, print it.

Below is the implementation of the above approach:  

C++




// C++ program to display first N Prime numbers
#include <bits/stdc++.h>
using namespace std;
 
// Function to print first N prime numbers
void print_primes_till_N(int N)
{
    // Declare the variables
    int i, j, flag;
 
    // Print display message
    cout << "\nPrime numbers between 1 and "
         << N << " are:\n";
 
    // Traverse each number from 1 to N
    // with the help of for loop
    for (i = 1; i <= N; i++) {
 
        // Skip 0 and 1 as they are
        // niether prime nor composite
        if (i == 1 || i == 0)
            continue;
 
        // flag variable to tell
        // if i is prime or not
        flag = 1;
 
        for (j = 2; j <= i / 2; ++j) {
            if (i % j == 0) {
                flag = 0;
                break;
            }
        }
 
        // flag = 1 means i is prime
        // and flag = 0 means i is not prime
        if (flag == 1)
            cout << i << " ";
    }
}
 
// Driver code
int main()
{
 
    int N = 100;
 
    print_primes_till_N(N);
 
    return 0;
}

Java




// Java program to display
// first N Prime numbers
class GFG
{
     
// Function to print first N prime numbers
static void print_primes_till_N(int N)
{
    // Declare the variables
    int i, j, flag;
 
    // Print display message
    System.out.println("Prime numbers between 1 and "
                                      + N + " are:");
 
    // Traverse each number from 1 to N
    // with the help of for loop
    for (i = 1; i <= N; i++)
    {
 
        // Skip 0 and 1 as they are
        // niether prime nor composite
        if (i == 1 || i == 0)
            continue;
 
        // flag variable to tell
        // if i is prime or not
        flag = 1;
 
        for (j = 2; j <= i / 2; ++j)
        {
            if (i % j == 0)
            {
                flag = 0;
                break;
            }
        }
 
        // flag = 1 means i is prime
        // and flag = 0 means i is not prime
        if (flag == 1)
            System.out.print(i + " ");
    }
}
 
// Driver code
public static void main (String[] args)
{
    int N = 100;
 
    print_primes_till_N(N);
}
}
 
// This code is contributed by AnkitRai01

Python3




# Python3 program to display first N Prime numbers
 
# Function to print first N prime numbers
def print_primes_till_N(N):
 
    # Declare the variables
    i, j, flag = 0, 0, 0;
 
    # Print display message
    print("Prime numbers between 1 and ",
                            N , " are:");
 
    # Traverse each number from 1 to N
    # with the help of for loop
    for i in range(1, N + 1, 1):
 
        # Skip 0 and 1 as they are
        # niether prime nor composite
        if (i == 1 or i == 0):
            continue;
 
        # flag variable to tell
        # if i is prime or not
        flag = 1;
 
        for j in range(2, ((i // 2) + 1), 1):
            if (i % j == 0):
                flag = 0;
                break;
 
        # flag = 1 means i is prime
        # and flag = 0 means i is not prime
        if (flag == 1):
            print(i, end = " ");
 
# Driver code
N = 100;
print_primes_till_N(N);
 
# This code is contributed by Rajput-Ji

C#




// C# program to display
// first N Prime numbers
using System;
     
class GFG
{
     
// Function to print first N prime numbers
static void print_primes_till_N(int N)
{
    // Declare the variables
    int i, j, flag;
 
    // Print display message
    Console.Write("Prime numbers between 1 and " +
                                   N + " are:\n");
 
    // Traverse each number from 1 to N
    // with the help of for loop
    for (i = 1; i <= N; i++)
    {
 
        // Skip 0 and 1 as they are
        // niether prime nor composite
        if (i == 1 || i == 0)
            continue;
 
        // flag variable to tell
        // if i is prime or not
        flag = 1;
 
        for (j = 2; j <= i / 2; ++j)
        {
            if (i % j == 0)
            {
                flag = 0;
                break;
            }
        }
 
        // flag = 1 means i is prime
        // and flag = 0 means i is not prime
        if (flag == 1)
            Console.Write(i + " ");
    }
}
 
// Driver code
public static void Main (String[] args)
{
    int N = 100;
 
    print_primes_till_N(N);
}
}
 
// This code is contributed by Rajput-Ji
Output: 
Prime numbers between 1 and 100 are:
2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97


 

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