SPOJ Number theory Problem PRIME1 - Prime Generator Solution

Problem Link:  https://www.spoj.com/problems/PRIME1/

Solve in C++:

///La ilaha illellahu muhammadur rasulullah

///******Bismillahir-Rahmanir-Rahim******///

///Abul Hasnat  Tonmoy

///Department of CSE,23rd batch

///Islamic University,Bangladesh

///**********ALLAH IS ALMIGHTY************///

#include<iostream>

#include<math.h>

#include<stdio.h>

using namespace std;

bool checkprime (long int num)

{

    if (num <=1)

        return false;

    else if (num == 2)

        return true;

    else if (num % 2 == 0)

        return false;

    else

    {

        bool prime = true;

        int divisor = 3;

        int upperLimit =sqrt(num) +1;

        while (divisor <= upperLimit)

        {

            if (num % divisor == 0)

                return false;

            divisor +=2;

        }

        return prime;

    }

}

int main()

{

    int a,b,i,n,j;

    scanf("%d",&n);

    for(i=0; i<n; i++)

    {

        scanf(" %d %d",&a,&b);

        printf("\n");

        for(j=a; j<=b; j++)

        {

            if(checkprime(j))

                printf("%d\n",j);

        }

    }

    return 0;

}