home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Frozen Fish 1: Amiga
/
FrozenFish-Apr94.iso
/
bbs
/
gnu
/
groff-1.09-src.lha
/
src
/
amiga
/
groff-1.09
/
libgroff
/
prime.cc
< prev
next >
Wrap
C/C++ Source or Header
|
1991-05-20
|
385b
|
27 lines
#include <math.h>
int is_prime(unsigned n)
{
if (n <= 3)
return 1;
if (!(n & 1))
return 0;
if (n % 3 == 0)
return 0;
unsigned lim = unsigned(sqrt((double)n));
unsigned d = 5;
for (;;) {
if (d > lim)
break;
if (n % d == 0)
return 0;
d += 2;
if (d > lim)
break;
if (n % d == 0)
return 0;
d += 4;
}
return 1;
}