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

void my_function(char **); // Change char* to char**

int main(int argc, char *argv[]) {
    char *ptr;
    ptr = malloc(10);

    if(ptr != NULL) printf("FIRST TEST: ptr is not null\n");
    else printf("FIRST TEST: ptr is null\n");

    my_function(&ptr); //You pass a char**

    if(ptr != NULL) printf("SECOND TEST: ptr is not null\n");
    else printf("SECOND TEST: ptr is null\n");
}

void my_function(char **a) {  //Change char* to char** here
    *a = NULL;
}