Prime numbers

[strling]

Hello!I was trying to write a program that shows all the prime numbers smaller than n.However,something strange happens.When n is 10,for example,the program shows "2 5 7" (missing 3). If n is 100, the program shows all the prime numbers smaller than 100 except 3,5 and 7.What am I doing wrong?

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    int n,j,i,t=1;
    cin>>n;
    for(j=1;j<n;j++)
       {t=1;
        if(j<=1||(j%2==0&&j!=2))
        t=0;
        else
        {
            for(i=3;i<=((int)sqrt((double)n));i=i+2)
                if (j%i==0){ t=0;
                            break;}
        }

        if (t==1)cout<<j<<endl;
      
       }
       
    return 0;
}

[bheadmaster]

for(i=3;i<=((int)sqrt((double)n));i=i+2)
    if (j%i==0){ t=0;
                break;}

For every n that is higher than 3, this code will automatically leave out the number 3 (because i is initialized as 3, and if j is 3, the if loop will be true and t will be set to 0 so that j (which is 3) will not be printed out.


IMHO, this is a not a good prime number generator algorithm, but then again I can't see the idea in your head, so you might be on to something that I can't see.

[bheadmaster]

In fact, it will leave out every prime number lower than square root of n.
That's why when you enter 100, you get all prime numbers except 3, 5, and 7 (since square root of 100 is 10).