BSArch/01/prime.c

#include <stdio.h>

#define PRINTPRIME(x) if(is_prime(x)) printf("%i\n", x)
#define PRINTERROR(message) printf("ERROR: %s\n", message)

// check for prime number
int is_prime(int number)
{
        int i;
        for (i=2; i*i <= number; i++) {
                if ((number % i) == 0)
                        return 0;
        }
        return 1;
}

int main(int argc, char * argv[])
{
        
        // TODO: segfaults if zero arguments given
        // switch/case???
        if (argc == 1) {
                PRINTERROR("No arguments given, will segfault under cygwin. :-)");
        }
        
        // (3) range mode
        if (argc > 2) {
                int i, j;
                j = atoi(argv[2]);
                for (i = atoi(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) {
                        PRINTPRIME(atoi(argv[1]));
                
                // (2) file mode: read numbers from file
                } else {
                        char num[11];
                        while (fgets(num, 11, fp))
                                PRINTPRIME(atoi(num));
                        fclose(fp);
                }
        }
}
1	joko	1.1	#include <stdio.h>
2	joko	1.3
3	joko	1.4	#define PRINTPRIME(x) if(is_prime(x)) printf("%i\n", x)
4			#define PRINTERROR(message) printf("ERROR: %s\n", message)
5
6			// check for prime number
7			int is_prime(int number)
8	joko	1.1	{
9	joko	1.4	int i;
10			for (i=2; i*i <= number; i++) {
11			if ((number % i) == 0)
12			return 0;
13			}
14			return 1;
15	joko	1.1	}
16	joko	1.3
17	joko	1.1	int main(int argc, char * argv[])
18			{
19	joko	1.4
20			// TODO: segfaults if zero arguments given
21			// switch/case???
22			if (argc == 1) {
23			PRINTERROR("No arguments given, will segfault under cygwin. :-)");
24			}
25
26			// (3) range mode
27			if (argc > 2) {
28			int i, j;
29			j = atoi(argv[2]);
30			for (i = atoi(argv[1]); i< j; i++) {
31	joko	1.1	PRINTPRIME(i);
32			}
33	joko	1.4
34			// other modes
35			} else {
36
37			// try to open file for reading
38			FILE * fp = fopen(argv[1], "r");
39
40			// (1) test-single-number mode: first argument is not a filename
41			if (fp == NULL) {
42	joko	1.1	PRINTPRIME(atoi(argv[1]));
43	joko	1.4
44			// (2) file mode: read numbers from file
45			} else {
46			char num[11];
47			while (fgets(num, 11, fp))
48	joko	1.1	PRINTPRIME(atoi(num));
49			fclose(fp);
50			}
51			}
52			}
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