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main.c
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main.c
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#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <errno.h>
#include <string.h>
#include "collatz.h"
#define REDC "\e[31m"
#define OFFC "\e[0m"
static void
usage(const char * progName) {
assert(progName != NULL);
fprintf(stderr, "Usage: %s <n>\n\nWhere n is an unsigned integer value.\n", progName);
}
typedef unsigned long ulong_t;
int main(int argc, char *argv[]) {
char *ep=NULL;
ulong_t n;
ulong_t steps;
puts("Collatz Conjecture tester");
// There should only be one argument
if (argc != 2) {
usage(argv[0]);
fputs( REDC "There should only be one argument\n" OFFC, stderr);
return EXIT_FAILURE;
}
// Make sure arg is not negative
for (char *c = argv[1]; *c; c++) {
if (*c == '-') {
usage(argv[0]);
fprintf(stderr, REDC "error: n cannot be negative number\n" OFFC);
return EXIT_FAILURE;
}
else if (*c >= 48 && *c <= 57)
break;
}
n = strtoul(argv[1], &ep, 10);
fprintf(stderr, "\x1b[1;30mn = %lu\x1b[0m\n", n );
if (!n || errno || *ep) {
usage(argv[0]);
if (errno)
fprintf(stderr, REDC "%s: %s\n" OFFC, argv[1], strerror(errno));
else if (ep && *ep)
fprintf(stderr, REDC "%s (I don't understand the part starting with \"%s...\")\n" OFFC, argv[1], ep);
else if (!n)
fprintf(stderr, REDC "%s (must be non-zero)\n" OFFC, argv[1]);
else
fputs(REDC "Unknown error: please open an issue at\n\nhttps://github.com/mojotx/collatz-c/issues\n" OFFC, stderr);
return EXIT_FAILURE;
}
for (steps=0; n != 1; steps++) {
printf("%lu ", n);
n = collatz(n);
}
puts("1");
printf("steps: %lu\n", steps);
}