Testing c plus plus code prime number?

Answer 1

Use the following function to determine if a whole number is prime, including negative values:

bool isprime(int p)

{

if(p<0)

p*=(-1); // convert to positive integer

if( p<2 ( p>2 && p&1==0 ))

return( false );

int max = (int)sqrt((double) p)+1;

for( int i=3; i<=max; i+=2 )

if( p%i==0 )

return( false );

return( true );

}