BSArch/01/prime.c

/* $Id: prime.c,v 1.8 2006/05/12 23:38:15 joko Exp $ */

#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include <errno.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, 0 and 1 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) {
        
        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(EXIT_FAILURE);
        }
        
        return number;
        
}

int main(int argc, char * argv[])
{
        
        if (argc == 1) {
                PRINTERROR("No arguments given.");
                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; 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	/* $Id: prime.c,v 1.8 2006/05/12 23:38:15 joko Exp $ */
2
3	#include <stdio.h>
4	#include <stdlib.h>
5	#include <limits.h>
6	#include <errno.h>
7
8	#define BOOL int
9	#define TRUE 1
10	#define FALSE 0
11
12	#define PRINTPRIME(x) if (is_prime(x)) printf("%i\n", x)
13	#define PRINTERROR(message) fprintf(stderr, "ERROR: %s\n", message)
14
15	/* check for prime number */
16	BOOL is_prime(long int number)
17	{
18	int i;
19
20	/* negative values, 0 and 1 are never prime numbers */
21	if (number < 2) return FALSE;
22
23	/* check all numbers 2..sqrt(number) for being a prime number */
24	for (i=2; i*i <= number; i++) {
25	if ((number % i) == 0)
26	return FALSE;
27	}
28	return TRUE;
29	}
30
31	/* convert from string to long int, with error checking */
32	long int convert_number(const char *nptr) {
33
34	errno = 0;
35	char * endptr;
36	long int number = strtol(nptr, &endptr, 10);
37
38	/* invalid characters? */
39	if (*endptr != '\0') {
40	char message[254];
41	snprintf(message, 256, "Could not convert '%s' to a valid number.", nptr);
42	PRINTERROR(message);
43	exit(EXIT_FAILURE);
44	}
45
46	/* invalid range? */
47	/* if (number == LONG_MAX \|\| number == LONG_MIN) { */
48	if (errno == ERANGE) {
49	char message[254];
50	snprintf(message, 256, "Number is not in range of 'long int': %s", nptr);
51	PRINTERROR(message);
52	exit(EXIT_FAILURE);
53	}
54
55	return number;
56
57	}
58
59	int main(int argc, char * argv[])
60	{
61
62	if (argc == 1) {
63	PRINTERROR("No arguments given.");
64	exit(EXIT_FAILURE);
65	}
66
67	/* (3) range mode */
68	if (argc > 2) {
69	long int i, j;
70	i = convert_number(argv[1]);
71	j = convert_number(argv[2]);
72	for (i; i< j; i++) {
73	PRINTPRIME(i);
74	}
75
76	/* other modes */
77	} else {
78
79	/* try to open file for reading */
80	FILE * fp = fopen(argv[1], "r");
81
82	/* (1) test-single-number mode: first argument is not a filename */
83	if (fp == NULL) {
84	long int number = convert_number(argv[1]);
85	PRINTPRIME(number);
86
87	/* (2) file mode: read numbers from file */
88	} else {
89	char entry[11];
90	while (fgets(entry, 11, fp)) {
91	long int number = convert_number(entry);
92	PRINTPRIME(number);
93	}
94	fclose(fp);
95	}
96	}
97	}
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