Use of # symbol in C

Question

I'm taking on an online C language test (not for a job, just for on my own) and I keep running into questions of this type using the hash symbol. I am assuming its not a typo and I am not familiar with this use of a hash symbol.

#include <stdio.h>
int* func()
{
    int num = 10;
    return #
}
int main()
{
    int *ptr = func();
    printf("%d\n", *ptr);
    return 0;
}

What is the output of the above C code?

The answer is that it is a runtime error and the explanation is

The variable defined in a function will be allocated in stack segment, which will be removed when the function returns. So accessing the address of those variables results in segmentation fault.

Answer 1

Whoever created the test didn't properly encode their HTML. What they wanted that line to look like is:

return #

They put that directly into the HTML of the test page, forgetting that &XXX; is how HTML entities are entered. # is the entity for the # character. They should have written:

return #

& is the entity for the & character.