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Prime numbers

AligatorAligator Posts: 9Member
Woul someone please tell me how to obtain prime numbers between 1 and 100 using java.

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  • rhemminkrhemmink Posts: 16Member
    : Woul someone please tell me how to obtain prime numbers between 1 and 100 using java.
    :

    import java.lang.Math;
    class prime


    {
    public static void main(String args[])


    {
    for (int i = 2; i <= 100; i++)


    {
    boolean isprime=true;
    if (i == 2) System.out.println(i);
    if (i%2 == 0) continue;
    for (int j= 3; j<=Math.sqrt(i); j++)
    if (i%j == 0)


    {
    isprime=false;
    break;
    }
    if(isprime)System.out.println(i);
    }
    }
    }
  • ManningManning Posts: 1,621Member
    [b][red]This message was edited by Manning at 2004-6-23 18:42:5[/red][/b][hr]
    : : Woul someone please tell me how to obtain prime numbers between 1 and 100 using java.
    : :
    :
    [code]
    : import java.lang.Math;
    : class prime
    : {
    : public static void main(String args[])
    : {
    : for (int i = 2; i <= 100; i++)
    : {
    : boolean isprime=true;
    : if (i == 2) System.out.println(i);
    : if (i%2 == 0) continue;
    : for (int j= 3; j<=Math.sqrt(i); [red]j+=2[/red])
    : {
    : if (i%j == 0)
    : {
    : isprime=false;
    : break;
    : }
    : }
    : if(isprime)System.out.println(i);
    : }
    : }
    : }
    [/code]

    Just thought I would throw in a nice easy tweak to improve the speed. Going from 1 to 100 you won't even notice the difference it makes, but with larger numbers that small change can give a huge improvement.

    And of course there are ways to make it even faster, but they would require more than 2 characters to change :)




  • globalprogglobalprog Posts: 67Member
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