Find prime no.

Question

using while loop

Answer 1

//check the accepted number is prime number or not.

#include<stdio.h>
#include<conio.h>
void main()
{
int n,c=1,i;
clrscr();
printf("enter the number= ");
scanf("%d",&n);

i=2;
while(i<=n-1)
{
if(n%i==0)
{
c=0;
}
i++;
}
if(c==0)
{
printf("%d is Not a prime number",n);
}
else
{
printf("%d is Prime number",n);
}
getch();
}

Answer 2

#include<iostream.h>
#include<math.h>
int main()
{
int no,flag,x=2;
cout<<"Enter number";
cin>>no;
while(x<=no)
{
int i=2;
flag=0;
while(i<=floor(sqrt(x)))
{
if(x%i==0)
flag=1;
i++;
}
if(flag==0)
cout<<x<<endl;
x++
}
return 0;
}

Answer 3

#include <iostream>
using namespace std;

int main() {
int i,n,j,flag;
n=5;
i=2;
flag=1;
while(i<=n)
{

j=2;
while(j<=i-1)
{
if(i%j==0){
flag=0;
break;
}
j++;
}
if(flag){
cout << "your prime number " << i << endl;
}

i++;
}
return 0;
}

Answer 4

#include <iostream>
using namespace std;

int isPrime(int no)
{
if(no == 1 || no == 0)
return 0;
int i=2;
while(i<no){
if(no % i == 0)
return 0;
i++;
}
return 1;
}

int main() {

int no;
cin>>no;
if(isPrime(no))
cout<<"prime"<<endl;
else
cout<<"not prime ";
return 0;
}