C++ program to print prime numbers [New]

In this program, we will make a c++ program to print prime numbers upto n.

• Prime numbers up to n
• Prime numbers between 1 to 100
• Prime numbers in a given range

Basic knowledge required: for-loop & if-else.

C++ program to print prime numbers upto n

We have to print prime numbers from 1 to n, where n is the upper range. The user gives the upper range according to their choice.

#include<iostream> 
using namespace std; 
int main() 
{ 
    int n,i,j; 
    cout<<"Enter upper range:"; 
    cin>>n; 
    cout<<"\n Prime Numbers from 1 to "<<n<<": "; 
    for(i=1;i<=n;i++) 
    { 
        for(j=2;j<=i;j++) 
        {  
            if(i%j==0) 
            break; 
        } 
    if(i==j) 
    cout<<j<<" "; 
    } 
return 0; 
}

Output:
Enter upper range:50
Prime Numbers from 1 to 50: 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47

Print prime numbers between 1 and 100

This program will print prime numbers from 1 to 100.

#include<iostream> 
using namespace std; 
int main() 
{ 
    int i,j; 
    cout<<"\n Prime Numbers from 1 to 100: "; 
    for(i=1;i<=100;i++) 
    { 
        for(j=2;j<=i;j++) 
        { 
            if(i%j==0) 
            break; 
        } 
    if(i==j) 
    cout<<j<<" "; 
    } 
return 0; 
}

Output:
Prime Numbers from 1 to 100: 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

C++ program to print prime numbers in a given range

In this program, we have to display prime numbers in a given range, i.e., lower and upper limits. The lower limit, as well as the upper limit, is provided by the user according to their choice.

#include<iostream>
using namespace std;
int main()
{
    int l,u,i,j;
    cout<<"Enter lower limit:";
    cin>>l;
    cout<<"Enter upper limit:";
    cin>>u;
    cout<<"\n Prime Numbers from "<<l<<" to "<<u<<": ";
    for(i=l;i<=u;i++)
    {
        for(j=2;j<=i;j++)
        {
            if(i%j==0)
            break;
        }
    if(i==j)
    cout<<j<<" ";
    }
return 0;
} 

Output:
Enter lower limit:10
Enter upper limit:50
Prime Numbers from 10 to 50: 11 13 17 19 23 29 31 37 41 43 47

Find Prime Numbers From 1 to N

Given a number N, find number of primes in the range [1,N].

#include<bits/stdc++.h>
using namespace std;
int checkPrime(int n)
{
    //factors of 10 are 1,2,5,10
    /* 10-1*10, 2*5,5*2,10*1
    so we can run loop from 1 to sqrt(n)*/ 
    //factors of 7 - 1,7
    //for prime numbers, there are only two factors
    int c=0;
    for(int i=1;i*i<=n;i++)
    {
        if(n%i==0)
        {
            if(i*i==n)
                c+=1;
            else
                c+=2;
        }
    }
    if(c==2)
        return true;
    return false;
}
int main(){
    
    // write your code here
    int n;
    cin>>n;
    int count=0;
    for(int i=1;i<=n;i++)
    {
        if(checkPrime(i))
        {
            count++;
        }
    }
    cout<<count<<endl;
    return 0;
}

Input: 6
Output: 3
There are three prime numbers from 1 to 6 {2,3,5}.

How do you print all prime numbers in C++ using a do-while loop?

#include<iostream> 
using namespace std; 
int main() 
{ 
    int n,i,j; 
    cout<<"Enter upper range:"; 
    cin>>n; 
    cout<<"\n Prime Numbers from 1 to "<<n<<": "; 
    for(i=1;i<=n;i++) 
    { 
        int j=2;
        do
        {
            if(i%j==0)
                break;
            j++;
        }while(j<=i);
        if(i==j) 
        cout<<j<<" "; 
    } 
return 0; 
}

About this post:

Siddharth Jha makes this C++ program to print prime numbers up to n. If you have any queries related to this post, deliver your query in the comment box. We will reply to you as soon as possible.

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