#include <stdio.h>

int counter = 0;

int gcd(int a, int b) {
    counter++;
    if (a == 0) return b;
    if (b == 0) return a;
    return gcd(b, a % b);
}

int main(void) {
	int eastwood = 10164;
	char guevara = 240;
	printf("result: %d\n", gcd(guevara, eastwood) );                    
	printf("function calls needed: %d\n", counter);
	return 0;
}

#include <stdio.h>

void foo(int a) {
	a++;
}

int main(void) {
	int a = 5;
	foo(a);
	printf("%d", a);
	return 0;
}

#include <stdio.h>

struct student {
    int matrikelnummer;
    int alter;
    char name[64];
};

void rejuvenate(struct student s) {
	s.alter = 0;
}

int main(void) {
    struct student s1;

    s1.alter = 20;
    rejuvenate(s1);
    printf("s1.alter = %d\n", s1.alter);

    return 0;
}