main.c


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

int print_help(void) {
    printf("Usage: collatz <number>"
           "\nMade by samuel@yakubos.org\n\n");
    return 1;
}

int main(int argc, char *argv[]) {
    if ( argc < 2 || argc > 2) return print_help();

    char *endptr;
    int  int_number = strtol(argv[1], &endptr, 10);

    /* check the number for nonsense */
    if ( int_number <= 0 ) return print_help();
    unsigned long long long_num = int_number;

    int  steps = 0;
    while ( long_num > 1 ) {
        long_num = ( long_num & 1 ) ? long_num * 3 + 1 : long_num / 2;
        printf("%llu\n", long_num);
        steps++;
    }

    printf("%s took %d steps\n", argv[1], steps);
    
}