--- joko/Uni/BSArch/01/prime.c	2006/05/12 23:38:15	1.8
+++ joko/Uni/BSArch/01/prime.c	2006/05/13 09:20:36	1.9
@@ -1,8 +1,9 @@
-/* $Id: prime.c,v 1.8 2006/05/12 23:38:15 joko Exp $ */
+/* $Id: prime.c,v 1.9 2006/05/13 09:20:36 joko Exp $ */
 
 #include <stdio.h>
 #include <stdlib.h>
 #include <limits.h>
+#include <errno.h>
 
 #define BOOL int
 #define TRUE 1
@@ -16,7 +17,7 @@
 {
 	int i;
 	
-	/* negative values are never prime numbers */
+	/* negative values, 0 and 1 are never prime numbers */
 	if (number < 2) return FALSE;
 	
 	/* check all numbers 2..sqrt(number) for being a prime number */
@@ -29,13 +30,30 @@
 
 /* convert from string to long int, with error checking */
 long int convert_number(const char *nptr) {
-	long int number = strtol(nptr, (char **)NULL, 10);
-	if (number == LONG_MAX || number == LONG_MIN) {
+	
+	errno = 0;
+	char * endptr;
+	long int number = strtol(nptr, &endptr, 10);
+	
+	/* invalid characters? */
+	if (*endptr != '\0') {
+		char message[254];
+		snprintf(message, 256, "Could not convert '%s' to a valid number.", nptr);
+		PRINTERROR(message);
+		exit(EXIT_FAILURE);
+	}
+	
+	/* invalid range? */
+	/* if (number == LONG_MAX || number == LONG_MIN) { */
+	if (errno == ERANGE) {
 		char message[254];
 		snprintf(message, 256, "Number is not in range of 'long int': %s", nptr);
 		PRINTERROR(message);
-		exit(-1);
+		exit(EXIT_FAILURE);
 	}
+	
+	return number;
+	
 }
 
 int main(int argc, char * argv[])
@@ -43,14 +61,15 @@
 	
 	if (argc == 1) {
 		PRINTERROR("No arguments given.");
-		exit(-1);
+		exit(EXIT_FAILURE);
 	}
 	
 	/* (3) range mode */
 	if (argc > 2) {
 		long int i, j;
+		i = convert_number(argv[1]);
 		j = convert_number(argv[2]);
-		for (i = convert_number(argv[1]); i< j; i++) {
+		for (i; i< j; i++) {
 			PRINTPRIME(i);
 		}