--- joko/Uni/BSArch/01/prime.c	2006/05/12 20:38:15	1.5
+++ joko/Uni/BSArch/01/prime.c	2006/05/12 21:13:49	1.6
@@ -1,26 +1,40 @@
-/* $Id: prime.c,v 1.5 2006/05/12 20:38:15 joko Exp $ */
+/* $Id: prime.c,v 1.6 2006/05/12 21:13:49 joko Exp $ */
 
 #include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
 
-#define PRINTPRIME(x) if(is_prime(x)) printf("%i\n", x)
+#define BOOL int
+#define TRUE 1
+#define FALSE 0
+
+#define PRINTPRIME(x) if (is_prime(x)) printf("%i\n", x)
 #define PRINTERROR(message) fprintf(stderr, "ERROR: %s\n", message)
 
 /* check for prime number */
-int is_prime(int number)
+BOOL is_prime(long int number)
 {
 	int i;
 	for (i=2; i*i <= number; i++) {
 		if ((number % i) == 0)
-			return 0;
+			return FALSE;
+	}
+	return TRUE;
+}
+
+/* convert from string to long, with error checking */
+long int convert_number(const char *nptr) {
+	long int number = strtol(nptr, (char **)NULL, 10);
+	if (number == LONG_MAX) {
+		PRINTERROR("Number '%s' is not in range of 'long int'.");
 	}
-	return 1;
 }
 
 int main(int argc, char * argv[])
 {
 	
 	if (argc == 1) {
-		PRINTERROR("No arguments given, will segfault under cygwin. :-)");
+		PRINTERROR("No arguments given.");
 		return -1;
 	}
 	
@@ -40,7 +54,8 @@
 		
 		/* (1) test-single-number mode: first argument is not a filename */
 		if (fp == NULL) {
-			PRINTPRIME(atoi(argv[1]));
+			/* PRINTPRIME(atoi(argv[1])); */
+			PRINTPRIME(convert_number(argv[1]));
 		
 		/* (2) file mode: read numbers from file */
 		} else {