primary numbers finding

teasy

how I find one number if it is the primary number or not by recursion method in C++ language

TilakGopi

Hi,

Use the following function

bool IsPrime(int num)

{

for(int index = 2;index < =num/2;index++)

if(num%index == 0)

return false;

return true;

}

 

Thanx,

Ch.T.Gopi Kumar.

TilakGopi

Hi teasy,

It seems ur time is prime.

Is my lsPrime() functioning properly

Cheers,

Ch.T.Gopi Kumar.

teasy

thanks your answer but This answer that I want to find ,is not. My question should be solved by recursive function (it is not necessery working with for loop)

Keyu

call function as

IsPrime(num,2)

pass value of ur number here

bool IsPrime(int num,int index)

{

if(index < = num%2 )

if(num%index != 0)

{

index++;

IsPrime(num,index);

return false;

}

return true;

}

ok ..reply m if any probelm

byeee

TilakGopi

Oh,

 I couldn't get ur problem clearly.Sorry.Anyways ,here are 2 new answers.Have ur choice.

---------------------------------------------------------

//Method1

bool IsPrime(int num)

{

static int index = 2;

if(index>(num/2))

{

index = 2;

return true;

}

if(num%index == 0)

{

index = 2;

return false;

}

++index;

return IsPrime(num);

}

//Method2

/*bool IsPrime(int num,int index)

{

if(index>(num/index)) return true;  

if(num%index == 0) return false;

return IsPrime(num,++index);

}*/

int _tmain(int argc, _TCHAR* argv[])

{

for(int index = 2;index <1000;index++)

if(IsPrime(index) )

//or

//if(IsPrime(index,2))  //If u have chosen Method2

cout<<index<<" ";

}

-----------------------------------------

 

Cheers,

Ch.T.Gopi Kumar.

Damien Watkins - MSFT

Hello

Re question:

Such questions are outside the scope of this forum - for the scope of the VC General forum please look at: http://forums.microsoft.com/MSDN/ShowPost.aspx PostID=19445&SiteID=1 specifically where it says: "For general C++ questions or general development questions (unrelated to Microsoft implementation issues or features), please use your favorite general C++ or development forums or newsgroups.

OTP

Thanks

Damien