Passing by reference in C99?

Question

C++ / C#

#include "stdio.h"

int ap(int * a){
    return *a;
}

int al(int &a){
    return 1;
}

int main(){
    int a = 5;

    printf("%i", a);

    return 0;
}

Why only 1 option works?

1. g++ .\demo.c
   
2. gcc .\demo.c
   
3. gcc .\demo.c -std=c99
   

Answer 1

Links in C?? This is something new. Am I missing an update?
Because the first option compiles the code as C++.