C++ Program to Print Prime Numbers in a Given Range

This article contains C++ Program to Print Prime Numbers in a Given Range.

To understand this you need to understand these concepts :

1. C++ looping - for loop, while loop, do while loop

2. C++ Program to Check Whether a Number is Prime or Not

3. C++ Program to Find Prime Factors of a Number

Assume that user has entered a range of 10 to 20. Then prime numbers between 10 and 20 is 11, 13, 17, 19. You need to print these prime numbers using c++ programming code. 

C++ Program to Display Prime Numbers in a Given Range

#include<iostream>

using namespace std;

int main()

{

    int first,second,i,flag;

    cout<<"Enter first number : ";

    cin>>first;

    cout<<endl<<"Enter second number : ";

    cin>>second;

    if(first>second)

    {

        int t;

        t=first;

        first=second;

        second=t;

    }

    cout<<endl<<"Prime numbers between "<<first<<" and "<<second<<" : ";

    for(;first<=second;first++)

    {

        flag=0;

        for(i=2;i<first/2;i++)

        {

            if(first%i==0)

            {

                flag=1;

                break;

            }

        }

        if(flag==0)

        {

            cout<<first<<"\t";

        }

    }

    return 0;

}

OUTPUT 1:

Enter first number : 20

Enter second number : 30

Prime numbers between 20 and 30 : 23    29

OUTPUT 2:

Enter first number : 35

Enter second number : 45

Prime numbers between 35 and 45 : 37    41      43

OUTPUT 3:

Enter first number : 100

Enter second number : 85

Prime numbers between 85 and 100 : 89   97