In C, can an address of a pointer be 0? -

i'm reading solution problem in book cracking coding interview (q 1.2). objective there implement function void revers(char* str) in c reverses null terminating string.

the solution code looks this:

void reverse(char *str) {    char* end=str;    char tmp;    if(str)    {        while(*end)        {           end++;        }        end--;        //code reverse    } } 

here, str contains address right? , if(str) evaluate false if str 0, right?

so i'm saying is, there no chance str contain address 0x0000, evaluating if(str) false?

str indeed contain address (it's pointer char), , if(str) evaluate false iff str equal null pointer.

note null pointer not required standard refer address 0; however, standard mandates literal value of 0 when used in pointer context must interpreted compiler address of null pointer -- whatever might be.

this means test if(p == 0) guaranteed same if(p == null). also, conditional if(p) guaranteed same if(p != 0).

conclusion: code detect null pointer, but that's not technically same pointer points address 0 (even though in practice going find is).