BSArch/01/prime.c

/* $Id: prime.c,v 1.6 2006/05/12 21:13:49 joko Exp $ */

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>

#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 */
BOOL is_prime(long int number)
{
        int i;
        
        /* negative values are never prime numbers */
        if (number < 2) return FALSE;
        
        /* check all numbers 2..sqrt(number) for being a prime number */
        for (i=2; i*i <= number; i++) {
                if ((number % i) == 0)
                        return FALSE;
        }
        return TRUE;
}

/* 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) {
                char message[254];
                snprintf(message, 255, "Number is not in range of 'long int': %s", nptr);
                PRINTERROR(message);
                exit(-1);
        }
}

int main(int argc, char * argv[])
{
        
        if (argc == 1) {
                PRINTERROR("No arguments given.");
                exit(-1);
        }
        
        /* (3) range mode */
        if (argc > 2) {
                long int i, j;
                j = convert_number(argv[2]);
                for (i = convert_number(argv[1]); i< j; i++) {
                        PRINTPRIME(i);
                }
        
        /* other modes */
        } else {

                /* try to open file for reading */
                FILE * fp = fopen(argv[1], "r");
                
                /* (1) test-single-number mode: first argument is not a filename */
                if (fp == NULL) {
                        long int number = convert_number(argv[1]);
                        PRINTPRIME(number);
                
                /* (2) file mode: read numbers from file */
                } else {
                        char entry[11];
                        while (fgets(entry, 11, fp)) {
                                long int number = convert_number(entry);
                                PRINTPRIME(number);
                        }
                        fclose(fp);
                }
        }
}
1	joko	1.7	/* $Id: prime.c,v 1.6 2006/05/12 21:13:49 joko Exp $ */
2	joko	1.5
3	joko	1.1	#include <stdio.h>
4	joko	1.6	#include <stdlib.h>
5			#include <limits.h>
6	joko	1.3
7	joko	1.6	#define BOOL int
8			#define TRUE 1
9			#define FALSE 0
10
11			#define PRINTPRIME(x) if (is_prime(x)) printf("%i\n", x)
12	joko	1.5	#define PRINTERROR(message) fprintf(stderr, "ERROR: %s\n", message)
13	joko	1.4
14	joko	1.5	/* check for prime number */
15	joko	1.6	BOOL is_prime(long int number)
16	joko	1.1	{
17	joko	1.4	int i;
18	joko	1.7
19			/* negative values are never prime numbers */
20			if (number < 2) return FALSE;
21
22			/* check all numbers 2..sqrt(number) for being a prime number */
23	joko	1.4	for (i=2; i*i <= number; i++) {
24			if ((number % i) == 0)
25	joko	1.6	return FALSE;
26			}
27			return TRUE;
28			}
29
30	joko	1.7	/* convert from string to long int, with error checking */
31	joko	1.6	long int convert_number(const char *nptr) {
32			long int number = strtol(nptr, (char **)NULL, 10);
33	joko	1.7	if (number == LONG_MAX \|\| number == LONG_MIN) {
34			char message[254];
35			snprintf(message, 255, "Number is not in range of 'long int': %s", nptr);
36			PRINTERROR(message);
37			exit(-1);
38	joko	1.4	}
39	joko	1.1	}
40	joko	1.3
41	joko	1.1	int main(int argc, char * argv[])
42			{
43	joko	1.4
44			if (argc == 1) {
45	joko	1.6	PRINTERROR("No arguments given.");
46	joko	1.7	exit(-1);
47	joko	1.4	}
48
49	joko	1.5	/* (3) range mode */
50	joko	1.4	if (argc > 2) {
51	joko	1.7	long int i, j;
52			j = convert_number(argv[2]);
53			for (i = convert_number(argv[1]); i< j; i++) {
54	joko	1.1	PRINTPRIME(i);
55			}
56	joko	1.4
57	joko	1.5	/* other modes */
58	joko	1.4	} else {
59
60	joko	1.5	/* try to open file for reading */
61	joko	1.4	FILE * fp = fopen(argv[1], "r");
62
63	joko	1.5	/* (1) test-single-number mode: first argument is not a filename */
64	joko	1.4	if (fp == NULL) {
65	joko	1.7	long int number = convert_number(argv[1]);
66			PRINTPRIME(number);
67	joko	1.4
68	joko	1.5	/* (2) file mode: read numbers from file */
69	joko	1.4	} else {
70	joko	1.7	char entry[11];
71			while (fgets(entry, 11, fp)) {
72			long int number = convert_number(entry);
73			PRINTPRIME(number);
74	joko	1.5	}
75	joko	1.1	fclose(fp);
76			}
77			}
78			}
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