13. Program that inputs a number from the user and displays all prime numbers which are less that the input number using any loop.

Chapter 6: 

Looping Structures

Programming Exercise

Problem # 13:

Write a program that inputs a number from the user and displays all prime numbers which are less that the input number using any loop.

Solution:

#include<iostream>
#include<conio.h>
using namespace std;
int main()
{
    int c, n, num, p;
    cout<<"Enter a number upto which prime numbers are required:";
    cin>>n;
    for(num=2;num<n;num++)
    {
        p=1;
        for(c=2;c<=num/2;c++)
        if(num%c==0)
        {
            p=0;
            break;
        }
        if(p==1)
        cout<<num<<" ";
    }  
    return 0;
}

Let me know in the comment section if you have any question.

Previous Post:
12. Program that calculates and prints the average of several integers. Assume that the last value read is sentinel 9999.

Next Post:

14. Program that inputs a number from the user and displays its factorial. It asks the user whether he wants to calculate another factorial or not.