X-Git-Url: http://mj.ucw.cz/gitweb/?a=blobdiff_plain;ds=sidebyside;f=lib%2Fprime.c;h=eec6f5d3db0dd34881ce772a1560635c8f7619cf;hb=3e1e48b786ff2295ca6196253849b48d3a7f91b9;hp=56bcc87ef050573467861b416523a150718fdc3c;hpb=1571781022499a9d0c32d249f89945d034d1cbff;p=libucw.git

diff --git a/lib/prime.c b/lib/prime.c
index 56bcc87e..eec6f5d3 100644
--- a/lib/prime.c
+++ b/lib/prime.c
@@ -1,7 +1,10 @@
 /*
- *	Sherlock Library -- Prime Number Tests
+ *	UCW Library -- Prime Number Tests
  *
  *	(c) 1997 Martin Mares <mj@ucw.cz>
+ *
+ *	This software may be freely distributed and used according to the terms
+ *	of the GNU Lesser General Public License.
  */
 
 #include "lib/lib.h"
@@ -44,32 +47,32 @@ isprime(uns x)
 }
 
 uns
-nextprime(uns x)			/* Returns some prime greater than X, usually the next one or the second next one */
+nextprime(uns x)			/* Returns some prime greater than x */
 {
   x += 5 - (x % 6);			/* x is 6k-1 */
   for(;;)
     {
-      if (__isprime(x))
-	return x;
       x += 2;				/* 6k+1 */
       if (__isprime(x))
 	return x;
       x += 4;				/* 6k-1 */
+      if (__isprime(x))
+	return x;
     }
 }
 
 #ifdef TEST
 
 #include <stdio.h>
+#include <stdlib.h>
 
 int
 main(int argc, char **argv)
 {
   uns k = atol(argv[1]);
-  if (isprime(k))
-    printf("%d is prime\n");
-  else
-    printf("Next prime is %d\n", nextprime(k));
+  printf("%d is%s prime\n", k, isprime(k) ? "" : "n't");
+  printf("Next prime is %d\n", nextprime(k));
+  return 0;
 }
 
 #endif