// load array with divisors of c
    for (d = 1; d <= c; d++) {
        if (c % d == 0) { // correct
            printf("%i, %i\n", d, f); // prints correct

/* here is where it hangs and gets stuck. it can't hit the array
for whatever reason. f is initialized above to int f = 0;
without the printf it just sits there until it exits with nothing
in the array. f however does iterate as shown in the printf as well.
            c_array[f] = d;
            printf("%i\n", c_array[f]);
*/
            if (d == c / 2){ // correct
                printf("breaks here - %i", f);
                break;
            } else {
                f++;
                continue;
            }
        } else {
            continue;
        }
    }

    // holding location for divisors of c
    int c_array[c];

    // pre load array with 0. works, tested with printf added to loop
    for (int d = 0; d <= c; d++) {
        c_array[d] = 0;
    }

//ONE
#include <stdio.h>

int main()
{
    int n1, n2, i, gcd;

    printf("Enter two integers: ");
    scanf("%d %d", &n1, &n2);

    for(i=1; i <= n1 && i <= n2; ++i) {
        if(n1%i==0 && n2%i==0)
            gcd = i;
    }

    printf("G.C.D of %d and %d is %d", n1, n2, gcd);
    printf("\n");

    return 0;
}
/**********************************************************/

//TWO
#include <stdio.h>

int main()
{
    int n1, n2;
    
    printf("Enter two positive integers: ");
    scanf("%d %d",&n1,&n2);

    while(n1!=n2) {
        if(n1 > n2)
            n1 -= n2;
        else
            n2 -= n1;
    }
    
    printf("GCD = %d", n1);
    printf("\n");

    return 0;
}

//gcc gcd.c -o gcd

./gcd
Enter two integers: 81 153
G.C.D of 81 and 153 is 9
./gcd
Enter two integers: 8 12
G.C.D of 8 and 12 is 4

./gcd
Enter two positive integers: 153 81
GCD = 9
./gcd
Enter two positive integers: 8 12
GCD = 4
./gcd
Enter two positive integers: 100 20
GCD = 20

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

#define MAX_FACTORS 1024

static int factors[MAX_FACTORS];

size_t find_factors( int n )
{
	size_t count = 0;

	for ( int i = 2 ; i <= n / 2 ; i++ )
		if ( count < MAX_FACTORS )
		{
			if ( n % i == 0 )
				factors[count++] = i;
		} else {
			fprintf(stderr, "factors[] max array size exceeded. Aborted.\n");
			exit(EXIT_FAILURE);
		}

	return count;
}


int main( int argc, char *argv[] )
{
	if (argc < 2 )
		return 1;

	int arg = atoi(argv[1]);
	if ( arg < 1 )
		return 1;

	size_t n = find_factors(arg);
	if ( n == 0 )
		puts("Prime.");
	else
		for (size_t i = 0 ; i < n ; i++)
			printf("factor: %d\n",factors[i]);

	return 0;
}

    // pre load array with 0. works, tested with printf added to loop
    for (int d = 0; d <= c; d++) {

    for (int d = 0; d < c; d++) {

lq-factors.c:11:5: warning: 'num2' is used uninitialized in this function [-Wuninitialized]
   11 |     greatest_c_divisor(num1, num2);
      |     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

for(i=1; i <= n1 && i <= n2; ++i) {
        if(n1%i==0 && n2%i==0)
            gcd = i;
    }