How to pass a reference to a variable to a function in C (without pluses)?

Question

C++ / C#

There is a code example in C++:

void square(int x, int& result) {
    result = x * x;
}

What will be the analogue for Sei without pluses?

Answer 1

#include <stdio.h>

void square(int x, int *result) {
    *result = x * x;
}

int main() {
    int a = 5;
    printf("before: %d\n", a); // 5
    square(10, &a);
    printf("after: %d\n", a); // 100
    return 0;
}

Answer 2

void square(int x, int *result) {
    *result = x * x;
}

int main() {
    int r;
    square(10, &r);

    return 0;
}