type 'Null' is not a subtype of type 'String' in type cast flutter

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

int main() {
    char *str = NULL;
    int ptr = (int )str; // Type cast from pointer to char to pointer to int
    printf("%d", *ptr);   // Dereferencing the pointer and printing the value
    return 0;
}